Donnie has spent his life being a parent to his younger siblings, Raph, Leo, and Mikey, after their genetic donor saved them from draxum’s lab and gave his life for them. Donnie, having been thrust into caring from his siblings at a young age, is incredibly overprotective and paranoid about his siblings wellbeing. So when he comes across a rumor of draxum having made another mutant he can’t help but want to save them. He’s not great with emotions, his or others, but does his best for his family.