I bet later in the series, she wants to be a normal human being if she is not immune to retro-mutagenic or Donnatello manage to create another type of retro-mutagenic but then it will end up that she unfortunate come in contact with mutagen and mutates an anthropomorphic turtle. She had become accustomed, will choose to be a mutant turtle and become one of the ninja turtles, her headband would have been yellow since she goes with yellow clothes in most incarnations and it will be the possibility of Donatello to win her heart if he likes her whether she is a human or turtle.
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I don't think that will be the case, because so far they haven't made any changes to the show as major as that. Anyway, people don't really choose to become which mutant they want to be, it's really whatever they come into contact with first. It doesn't have to be an animal either, it could be trash like in that one episode whose name I forgot. At the same time, the mutagen is highly unpredictable. If she does come into contact with a turtle during the mutation, it doesn't guarantee that she will become an anthropomorphic turtle. It could range from gaining some attributes of a turtle to something completely different. In terms of writing, it's also unsound. For starters, April is one of the only connections the turtles have to the 'human' world. Taking her out of the equation would wreck everything off balance, and with Karai as the main focus lately, the writers and the turtles don't have time for any added distractions. Although, I guess it could happen if the writers are desperate for something new. That might happen towards the end of a season, when the past season's conflicts have been resolved and they need something to kick-start a new season.
Wow, that was long. That wasn't my intention at all, please forgive me! XD
(Edited by Toonfan752)