Mimmi is a Northern mermaid who came to the southern pod with unusual knowledge and powers. She is born to a powerful mermaid named Nerissa and is the sister of Zac. She is sweet, and although inclined to be reserved – some would even say shy – is super-intelligent and gifted. She has an insatiable thirst for knowledge and is excited to be on land discovering everything she can about land people and their lives. She is one of the main characters and is played by Allie Bertram.
Mimmi is a Northern mermaid, who came to live with the Mako pod in Australia and is the daughter of Nerissa. She and Ondina are loyal best friends. Although she typically follows Ondina's lead on things they do, she does not hesitate to speak up to her when she is out of line. There are also times where Mimmi cannot help but feel a little lonely since she has had no family of her own ever since her mother left. When she and Ondina return to Mako to try to save it for the pod, they are both soon introduced to Zac. Although she does not harbor the same sort of prejudice and resentment Ondina does, she is supportive of Ondina's belief that Zac's existence as a merman is a threat to the pod. When Zac insists that he does not need their help, Mimmi bursts in on Zac while he is changing clothes due to her lack of knowledge of land dweller norms in an attempt to explain the situation regarding the 7th moon cycle since Zac became a merman. Of course Zac is greatly bothered by Mimi's intrusion and resits her even more which causes Mimmi to think that Zac is unreasonable . She does however have enough reason to know that Ondina went too far when she attacked Zac unprovoked and is quick to point out that she was the one who started the fight and caused the chaos that ensued when Ondina blames the incident on Zac.
She later comes up with a plan to strip Zac of his powers with a potion that amplifies the full moon after luring him to the moon pool. Her plan backfires when Evie is turned into a mermaid as she attempts to rescue him. Mimmi soon learns to trust Zac much more quickly then Ondina does. This is particularly true after the group discovers a merman chamber in which Ondina disappears and Zac not only prevents Mimmi from suffering the same fate, but the two of them are able to work together to bring her back. When Ondina accused Zac of deceiving them, Mimmi insists to her that it was indeed an accident. Being a mermaid who "has to know everything," Mimmi is eager to learn as much about the world of land dwellers as she can.
Mimmi would also learn much more about herself during this experience. Throughout her time on land, it becomes apparent that she shares some sort of connection with Zac, as they share visions. At first, the mermaids and Zac believe that his connection to Mako Island is causing this. This theory is later proven incorrect and the connection is revealed to be not through Mako, but through blood. It turns out that Zac is actually the son of Nerissa and Mimmi's long lost brother.
This revelation shocks Mimmi, but she does not hesitate to protect Zac when Veridia attempts to do away with him during a confrontation in the merman chamber. Despite Veridia's orders, Mimmi refuses to move and she is soon joined by Ondina who knows full well that she would not deserve to call herself Mimmi's friend if she tried to force her to turn on her own flesh and blood. Although Mimmi and Ondina are cast out of the pod for this, Mimmi hardly cares as she has now found an important piece of her life she somehow always knew was missing and a family that she thought she never had. Unfortunately, Zac is not as enthusiastic about this as she is since it means his whole life has been a lie and he bitterly refuses to acknowledge her as his sister despite Ondina's pleas to listen to reason and Evie's comfort. Although somewhat saddened by her brother's rejection, Mimmi remains confident that he will eventually come around and accept her as his sister. Following this, Mimmi attempts to form a relationship with her newfound brother, but Zac still wants nothing to do with her. While trying to be understanding, Mimmi cannot help but feel a little frustrated since she is also hurting from having to grow up without any family due her own abandonment from their mother while Zac has had a family in the Blakley couple.
Rita offers her comfort, stating her strong belief that Nerissa only gave her and Zac up to keep them safe and that she had planned along to make sure they would find each other again one day. Later, when Zac unleashes his anger on two obnoxious lifeguards, Mimmi confronts him briefly on her own hardships and reminds him that he has had a family who loves him unlike her and therefore is much more lucky then he believes. After Zac is able to come to terms with who he is after talking with his parents, he is also finally able to accept Mimmi as his sister much to her delight. Throughout the second half of season 2, Mimmi is shown to have developed a strong bond with her brother similar to Sirena's bond with her sister Aquata that would only grow stronger for the remainder of the series. Both of them are shown to be extremely caring and protective of each other. As Zac's curiosity of the chamber grows, Mimmi refuses to go against his wishes and completely trusts that Zac will allow no harm to come to her or any mermaids. She also wanted to accompany Zac when he starts the chamber to ensure no harm comes to him either. Zac in return, did not want Mimmi to accompany him to ensure her safety and later surprises Mimmi when he decides to not go altogether when Rita informs him that he and Mimmi are descendants from the merman that built the chamber and refused to activate it after falling in love with a mermaid. However, Mimmi is unaware that Ondina had secretly talked Zac back into starting the chamber so that she can carry out a plan of Veridia's to destroy it in exchange for being allowed back into the pod. Mimmi soon realizes Zac and Ondina's deception when she has a vision and races to the chamber along with the others. They arrive just as Ondina is about to destroy the chamber and are able to talk her out of it after warning her that destroying the chamber may destroy the island along with it. As Zac then prepares to find out what the chamber does, he requests that Mimmi and the others leave to ensure their safety. Mimmi refuses this request, unwilling to leave him and risk him getting hurt. The group then learns that the chamber cannot start without the trident and so Veridia later lifts the girl's banishment much to their joy.
Mimmi also gains a love interest in a young man named Chris after deciding to get a job at the marine park. At first, he rubs her off the wrong and comes off to her as unreasonably strict when he scolds her for being in an employee only part of the park while talking to a dolphin. Later, she finds out that he has a passion for dolphins and dreams to work with them, but he is unable to form a connection. Mimmi resolves to help him and successfully gets him into the training program. They then share a kiss, but nothing apparently would come of it when she learns that he will be in America for 3 months. Though he assures her that they will see each other when he gets back.
Later, Mimmi would face more complications involving the people she cares about. As Ondina and Erik spend increasingly more time together, she also spends increasingly less time with Mimmi sparking jealousy. This would eventually cause them to have a fallout, although they do make up. Later, as the girls wait for the pod to return, Mimmi struggles with the possibility of never being able to venture on land again and having to give up on the only family she has ever had in Zac. Her strain only grows when Ondina decides to give up on the pod for Erik, causing a much worse fallout. They later make up after Sirena convinces them that although things would be different if Ondina stayed on land, they can still be close friends. The group then decide they must find a way to convince the pod that land people and mermen can be trusted so that they don't have to choose between the people they care about.
Danger soon starts to fill the air after the group discovers that the trident stone is the true key to starting the chamber and when Zac accidentally causes it to become active again. In the process, Mimmi is hurt by the stone when she touches it experiencing the life draining effect it has on mermaids. Despite Zac's and the mermaids best efforts, Erik is able to gain possession of the trident stone right in front of Mimmi. Mimmi tries to reason with him, but Erik refuses to give up, and soon Zac arrives to intervene having been alerted of the situation by a vision. However, Erik uses the stone to steal Zac's powers and render him unconscious as Mimmi looks on in horror. Erik is then able to escape with the stone while Mimmi tends to her brother. The next day as the mermaids contemplate what they can do to stop Erik, Mimmi suddenly has a vision showing her Zac being attacked by Erik for trying to take the stone from him and she rushes to aid him. However, by the time she arrives she finds Erik has already taken his leave and left Zac uninjured but deeply shaken. Despite Mimmi's attempts to encourage him, Zac seemingly gives up hope leaving it up to her, Ondina, and Sirena to stop Erik.
As they make their way to the chamber, Mimmi has another vision showing her that Zac has decided to try to stop Erik after all and is wrestling him for the stone. Mimmi then urges her friends to pick up the pace, knowing Zac will need help and won't be able to hold Erik for long. By the time they arrive, Erik has already succeeded in activating the chamber. The girls attempt to stop the chamber fails and it slowly begins to kill them as Zac watches in horror and Erik remorsefully tries to deactivate the chamber only to fail. Zac is able to stop the chamber and save the mermaids, but seemingly sacrifices his own life in the process. Mimmi is severely devastated by the apparent death of her beloved brother, crying strongly over the loss of her only family along with an equally heartbroken Evie. Desperate to save him, Mimmi puts her own safety at risk again when she attempts to use the stone to heal Zac while tearfully begging him not to leave her. She is successful and Zac's life and powers are restored, to her great relief and joy. The pod then returns to Mako and Mimmi swims off with the others to greet them, overjoyed at now being reunited with both her pod, and her brother.
Mimmi returns to her mermaid life with Ondina now that the pod has returned to Mako. With Sirena away on vacation with her sister, Mimmi and Ondina now frequently hang out with Evie and teach her more about mermaid life since she was given a moon ring. She also continues to make frequent trips on land to hang out at Rita's grotto and the cafe along with all the other new friends she made there such as Cam, Carly and most importantly, her brother Zac. Later, Mimmi and Ondina are introduced by Rita to a new mermaid from China named Weilan. Although Ondina takes an immediate disliking to her, Mimmi does everything she can to make her feel welcome. She later introduces Weilan to Zac and her other friends. As Mimmi, Ondina, and Evie prepare to take part in the full moon ceremony, they are suddenly approached by a 60 ft water dragon. Greatly alarmed, they attempt to fight it off with their moon rings but they have no effect on it. As Zac and Weilan arrive to help, they soon retreat to warn the pod. The mermaids and Zac then dedicate most of the season trying to find a way to destroy the dragon. As tension between Ondina and Weilan grows, Mimmi attempts to act as the peace maker. She tries to convince Weilan that Ondina is more kind hearted then she initially appears and convince Ondina that Weilan is on their side. In time, the two are able to make peace and begin to become friends.
As Mimmi and Ondina prepare to face the dragon, they are both frustrated when Veridia instead tasks them with looking after the younger mermaids instead of fighting with the pod. The two of them both decide to defy Veridia's orders and join the pod anyway. However, Mimmi remains unaware that Zac is secretly planning with Weilan to face the dragon himself to turn it's power back on itself with an eastern spell Weilan taught him, knowing full well that Mimmi would do everything she could to try to stop him if she knew. According to Zac during a conversation with Evie, Mimmi had apparently talked with Zac at some point off screen to let him know Veridia has a plan to stop the dragon, presumingly to convince him not to worry about her or the dragon and Zac presumingly pretends to be convinced. Mimmi and the rest of the pod are led astray by Weilan to hide on the opposite side of the ocean where the dragon will appear so Zac can carry out their plan. As the pod prepare to fight the dragon, Mimmi and Ondina soon begin to suspect something is wrong when the dragon does not appear to them despite the moon haven already risen. Mimmi soon realizes what is going on when she has a vision showing her that Zac is facing the dragon in the moon pool alone. Horrified at the thought of losing him the way she almost did in the merman chamber, Mimmi races to the moon pool to help him along with Ondina. However, by the time they arrive the damage has already been done. Although Zac and Evie are both uninjured, Evie has lost her tail at the dragons hands causing Weilan and Ondina to have a serious fallout. After a brief moment of pain over Evie's loss, they make up and Evie decides to take advantage of being an ordinary girl again.
During the season, Mimmi continues her work at the marine park where she is soon reunited with her love interest from the previous season Chris. Although they are both mutually interested in one another, they do not immediately pick up where they left off as Chris is nervous to ask her out. Eventually, Chris finally musters up the courage to ask her out and she happily accepts. However, Ondina is completely against the idea, her view of relationships having been tarnished since her experience with Erik. As Mimmi and Chris continue to enjoy themselves, they are constantly watched by Ondina despite Weilan's insistence to back off. As Mimmi and Chris are about to kiss, Ondina summons a rain storm, forcing Mimmi to flee. Ondina later realizes her mistake when Weilan is able to help her let go of the past and convince her that Mimmi needs to be free to make her own choices and mistakes. However, despite Ondina's apologies, Mimmi decides not to pursue a relationship with him feeling guilty for having to lie to him. However, Ondina and Weiian are able to get them back together after getting them both to come to a party. Chris and Mimmi then admit their true feelings for one another and finally become a couple.
Mimmi's bond with her brother also continues to grow stronger in season 3 and would later prove instrumental in the events of the season climax. In the episode "Wishful Thinking", Mimmi and the others are accidentally sent back in time five years into the past by a magical wishing shell as they look at a picture of Zac when he was younger and he wishes they could have seen him then. It is there that they meet a twelve year old Zac who has not yet fallen into the moon pool or learned of his merman heritage. He therefore does not recognize his friends and sister who are shocked upon realizing the young boy they see is a younger Zac and Weilan claims they are aliens much to young Zac's amazement. Although Weilan warns them that their interactions with young Zac must kept as minimal as possible to avoid possible changes in the future as they seek to retrieve the shell, Mimmi cannot help but find joy in meeting her brother during his childhood since it's a time of his life they did not have the chance to be together the way brothers and sisters are meant to. For the remainder of the girls time in the past, Mimmi would act as a motherly older sister figure to young Zac (which she actually is though Zac does not know this yet). As Mimmi kindly attempts to ask for young Zac's help finding the shell, she also highly disapproves when an impatient Ondina is mean to him, demanding he give them the shell and threatening to hurt him if he does not comply (despite not even knowing if he had even found it at all) which Mimmi sternly puts a stop to.
When Ondina finds the shell and young Zac pleas for them not to leave, Mimmi attempts to let him down gently by suggesting he get going as his mother calls him to leave for a birthday party for young Evie so he isn't late, figuring that it will be as if she had never left him once they have returned to their time. However, Mimmi is then forced to watch in sadness when young Zac leaves feeling hurt and dejected after Ondina intimidates him into not telling anyone they were there before coldly shooing him away. Mimmi scolds Ondina for her behavior towards him but Ondina dismisses this, just being satisfied that they got the shell. The mermaids then learn from a younger Rita that only the person who found the shell can use it, meaning they will be stuck in the past forever unless they can convince young Zac to help them. The girls soon find young Zac at young Evie's party but he orders them to leave him alone still hurt and angry over earlier. After making Ondina apologize for treating him badly and young Zac seemingly accepts her apology, Mimmi attempts to ask him for his help which he seems willing and eager to do. When the other guests take notice of the girls pretense and young Zac begs them to prove to the them they are aliens, Mimmi has no choice but to feign ignorance, unintentionally hurting young Zac worse then Ondina did by causing everyone to laugh at him and he runs off in humiliation. Mimmi then requests the other girls to give her a moment to talk to young Zac alone. Mimmi apologizes to young Zac for embarassing him and tries to convince him to help her and the others by explaining that he is the only one who can help them because he is special. She then reveals she is from the future and goes on to tell him how important he is to her revealing that they are close in the future, lightly hinting that they are siblings. However, young Zac is still upset for being humiliated in front of young Evie (who is just his crush at time) and shows no interest in helping at first. Mimmi then realizes just how much she upset young Zac and that it would not be fair to expect him to help her without helping him first. To prove her sincerity and make up for the previous grief they caused him, Mimmi offers to help young Zac before he helps her. This causes young Zac to feel a little better and begin to trust the "alien" he would learn is his sister later in his life as she proceeds to affectionately nuzzle with him. Mimmi then risks exposure by performing a magic show with her powers in front of the guests to save young Zac's reputation and impress young Evie. Afterwards, young Zac is reluctant to say goodbye to Mimmi after she had been so kind to him, but she reassures him and promises they will meet again in the future as they share a pinky swear. Mimmi then returns to the present with the others, thrilled to have had the opportunity to bond with Zac all over again. Young Zac's memory of the encounter is then erased, setting the stage for his true reunion with Mimmi in season 2.
During the second half of season 3, Mimmi's and Zac's past begins to haunt them as they both share a vision of a mermaid who Mimmi believes is their long lost mother Nerissa. She later learns from Weilan and Rita that the reason Nerissa left her and Zac was to stop an evil mermaid named Aurora from terrorizing the eastern and northern pod and that she disappeared when she went to face her. Much to Mimmi's frustration, the others are hesitant to believe that Nerissa really is out there. This causes Mimmi's feelings of loneliness that she felt before she had met Zac to resurface again. She is especially frustrated by Zac's skepticism since he saw her too, but Zac warns her that she should not get her hopes up too high untill they know for certain what these visions mean. Later, as Mimmi attends a football game Chris is playing in along with Ondina, Weilan and Zac, her moon ring begins to glow on it's own again. Believing that Nerissa is using it to make a connection with her, Mimmi prepares to leave the game and attempt the same thing while urging Zac to come with her. Knowing Chris will be crushed if Mimmi leaves, Zac refuses and sternly tells Mimmi that she needs to let Nerissa go. The conversation soon turns into an argument as Mimmi accuses Zac of not really caring whether Nerissa is alive or not since he has his own parents while she has no one.
Slightly offended by this remark, Zac reminds her that she has him. After offering one last chance to come along, Mimmi leaves on her own disgusted by Zac's lack of faith. Out at sea, Mimmi is horrified when her attempts to reach Nerissa with her moon ring summon the dragon and chases her into the canal leaving her trapped. After trying desperately to escape onto land, Zac and the other mermaids arrive but are unable to rescue her. The dragon then approaches a terrified Mimmi but leaves without taking her tail the same way it did to Zac. Afterwards, Zac comforts Mimmi as she recovers from her close call with the dragon and sheds tears over the pain of missing their mother. With a heavy heart, Mimmi decides that Zac was right and that she must let Nerissa go for both of their sake. In attempt to give themselves some closure, Mimmi and Zac hold a memorial service in Nerissa's honor as Zac holds her close. Afterwards, Mimmi apologizes for leaving Chris, but he begins to have doubts about their relationship.
Close to the season climax, the mermaids find a potential solution to defeat the dragon. While attending a book signing of a world famous treasure hunter named Rikki Chadwick with Chris, they notice a dragon bracelet that is associated with an ancient Chinese legend known as the Jao Long Dragon. Believing it can slay the dragon, the mermaids ask Riki for the bracelet, but she turns them away and has them thrown out. As Chris questions Mimmi on what had happened, she is unable to give a straight answer further straining their relationship. The girls later enlist Zac's help to steal it, but the heist is ultimately unsuccessful. When Mimmi next meets Chris, he demands to know what is going on but Mimmi refuses to tell him the truth. Fed up with her lack of honesty, Chris breaks up with Mimmi much to her heartbreak. Although greatly depressed over the breakup, Mimmi ultimately decides it is for the best. She is later comforted by Zac who is quickly able to cheer her up.
Another vision of Nerissa then appears, but this time she speaks to them and Zac is able to see her too. At the same time, Weilan finds out that the Jao Long dragon was a actually a human under a spell who was set free when a mermaid used the dragon bracelet which she discloses to Mimmi and Zac. Mimmi and Zac then conclude that their mother under the same kind of spell. The two of them have a meeting with Veridia begging her to cancel their plan to destroy the dragon and allow them to try to save her, but Veridia refuses unwilling to risk the safety of the pod. However, Weilan and Ondina are able to get the bracelet. As the group decides who should use it, Mimmi ultimately decides to do it after Zac volunteers first only to find out that only a mermaid can use it. As the group prepare to face the dragon for the final time, they look on in horror as the dragon is struck by lighting from a magic storm conjured by the mermaid council. Mimmi then attempts to use the bracelet and it seems to work as both she and Zac begin to feel Nerissa's presence. However, the storm continues to strike the dragon and seemingly begins to destroy it as Mimmi desperately cries out to her mother. Both she and the dragon then suddenly disappear, much to the horror of Zac and Ondina. After a moment, Mimmi emerges from the water along with a newly freed Nerissa and both she and Zac are finally reunited with her as they share a loving embrace.
At Rita's grotto, Nerissa explains that she was turned into the dragon during her confrontation with Aurora and she attacked the eastern pod under her orders before being placed in a deep sleep. She then reveals that it was Zac and Mimmi's ever increasing bond as siblings that allowed her to awaken and slowly begin to regain her sense of self. She then promises never to leave them again as Mimmi shares a hug with her newly reunited family, overjoyed at now having both her brother and her mother back.
Later, Mimmi meets with Chris and decides to tell him her secret. After revealing her true identity, Chris is overjoyed to learn she is a mermaid and immediately reestablishes his relationship with her. Afterwards, Mimmi thanks Rikki for letting her use the bracelet and offers to give it back, but she insists she keep it. Mimmi is then surprised to hear Ondina offer to join Weilan as she contemplates going back to China but she assures her that she is not leaving Mako forever. Mimmi accepts her decision, knowing that she can use the time she's away to catch up with Nerissa and continue to bond with Zac. Now back with her long lost family that she so desperately desired for many years, Mimmi knows in her heart that she will never feel lonely again.
Mimmi is a gorgeous mermaid from the Mako Island pod. Sweet, but self doubting and clumsy, she is extremely intelligent and always seems to be soaking up knowledge without even trying. She is also very loyal to the people she cares about, especially her best friend Ondina and her brother Zac.
Mimmi has long wavy brown hair, with very tanned skin and grey eyes. Like Sirena, she usually wears girly dresses and skirts and cute tops. Mimmi commonly wears outfits with flowers or nature-type patterns. Coincidentally, Mimmi is very similar in looks and wardrobe, to Cleo Sertori.
Mimmi possesses the ability to transform into a mermaid ten seconds after physical contact of water. She turns back into a human several minutes after climbing out of the the water and once her body is completely dry, she turns back into a human along with the clothes she was wearing before she transformed. As a mermaid, Mimmi has the ability to swim at a super speed of 600km/h, hold her breath for more than fifteen minutes, and dive deeper than any ordinary human being.
"In The Seventh Cycle", Mimmi and Ondina used this ability to send Cam flying.
Zac and Mimmi are able to share visions being siblings.
In "The Truth About Evie", When she sneezed, she produced a small patch of snow.
In "Surprise!" Mimmi used this power to lift a water bubble.
Mimmi used this power in "The Siren" to a heat Carly's phone.
- She regularly practices potions and spells using resources in Rita's grotto.
- She always wears a silver necklace with a dolphin pendant.
- She can speak to multiple different creatures including: humpback whale, northern penguin, and dolphin.
- She sings in the moon pool though not as often as Sirena does.
- She took a special class on enlargement in mermaid school.
- Because of Nerissa being her mother, she is considered an extremely powerful mermaid.
- Jonathan confirmed that Mimmi and Zac are not twins and that Mimmi is older. By how much is unclear.
- She is very similar to Cleo, both of them had a job at the marine park, and both of them are the brown haired in the iconic mermaid trio found on both H2O: Just Add Water and Mako: Island of Secrets.
- Due to being a Northern mermaid, she is probably immune to Snow Rash.
- Due to being a Northern mermaid she's immune to the Northern mermaid siren song.