Dogged Nice Guy: Played for Drama. With his mind frazzled post-mutation, Mutagen Man develops a fixation on April because she is routinely nice to him whenever she comes to visit. Being a 2-ton pile of acidic bile and solidified mutagen, this makes him especially dangerous when he literally wants to get his hands on her.
Hidden Agenda Hero: While Casey signing up April as his tutor goes just about the same as canon, here he has the secret motivation in finding out about what happened to Raphael, April being his brother's girlfriend making her the perfect mark to probe for info.
In Spite of a Nail: In "Mutagen Man Unleashed", Mutagen Man developed a fixation on April after Donnie vents to him about her, April having had a falling out with them after they accidentally mutated her father. While Mutagen Man still becomes obsessed with April, here it is because she regularly visits him in Donnie's lab.
Murder the Hypotenuse: Mutagen Man is convinced that April is his and that Donatello sucks as both a friend and a boyfriend.
Understanding Boyfriend: While Donnie offers to beat Casey up if he keeps bugging April, he trusts April enough to spend time alone with him as his tutor. When April commends him for not being crazy jealous over being alone with another guy, he points out that while he is jealous, his trust in April and her desperately needing to fix her dropping grades far outweighs his personal concerns.
