(Character makers used: Before / After was made with Missangest Antro Creator, which no longer functions outside of Flashpoint)
TMNT 2012 self-insert: Heather
Species: Human, later human/skunk mutant Pronouns: She/her Occupation: Mall store employee, later vigilante and member of the Mighty Mutanimals Love interest: Leatherhead
Heather enters the story as a human walking home from the closing shift at a legally-distinct Hot Topic. On her way home, she stumbles across a trio of Kraang-droids and gets caught when her curiosity causes her to lean too far forward while trying to eavesdrop. She's pursued by the Kraang and attempts to flee into the sewers out of desperation, but falls from the ladder while trying to free herself from the grip of one of the cyborgs. Injured and knocked unconscious from the fall, she's rescued by Leatherhead, who brings her to the Turtles' lair, hoping Donatello can treat her wounds.
Heather is initially shocked when she awakens, but she quickly accepts the mutants as allies after learning that Leatherhead saved her from the Kraang. While Heather spends the night, the two start to bond, and agree to see each other again later. Though Heather is returned to the surface and cautioned against seeking the mutants out again for her safety, she begins to meet up with Leatherhead in secret. Their bond deepens over the course of these meetings, but eventually, this leads to the Kraang learning about their alliance and following Heather to their usual meeting place.
When Heather tries to lead the Kraang away from her friend, she winds up getting captured after a wild skunk's spray causes her to blunder into a trap. Leatherhead chases her kidnappers down, but fails to catch them. He seeks the assistance of the Turtles, and together they follow the trail left by the skunk spray she was doused with. The mutants manage to break Heather out of Kraang custody, but not before a mutagen spill causes her to mutate into a skunk hybrid.
Now forced to live on the fringes of society with the other mutants of the city, she chooses to stay with Leatherhead...until an attempt to foil the Kraang's plans goes awry, and Leatherhead opts to venture to Dimension X to delay the invasion. Heather is devastated by the loss of her dear friend, and while staying with the Turtles, she begs Splinter to train her so that she can become strong enough to bring Leatherhead home.
She participates in many of the Turtles' endeavors until Leatherhead returns, forming close bonds with the Turtles and their friends along the way. When the Kraang launch a full-scale invasion of the city, she and Leatherhead come to Splinter's aid against Shredder, and are both soundly defeated. She and Leatherhead are discovered by Slash while he searches for the Turtles, and taken to the hideout of what later becomes the Mighty Mutanimals. She remains a member of the team through to the end of the series.