This might just be the angst gremlins setting up shop in my brain, but I can't help thinking that it's not just brotherly love behind why Donnie is taking sole custody of mug!Leo.
Because it's obviously not that he doesn't trust Raph or Mikey to look after Leo and keep him on ninpo life support. They could do it just as well, and even if Mikey still needs to be resting and restoring his energy, Raph is back up to full strength.
But one of the last bits of footage Donnie has of Leo is his twin reaching out to him (or at least reaching out to his memory in the lab) and asking for help, for care, and then apologizing for asking and saying it's not Donnie's concern or responsibility.
And this--Donnie not letting go or letting up for a second, going without sleep so that Leo is never alone or without energy--feels like him answering that call. It's him saying silently (until he can say it in person) that his twin is always his concern and he'll always answer if he can. Plus, he is the Fix-It Guy and this is his twin; he has to be the one to make it right. He couldn't help Leo then but he can help him now, and try to "make up" for the way he feels he let his family down.
Fictional turtles continue to consume my thoughts, more news at 11.
YOU
YOU ARE THE CHOSEN ONE WHO GET IT
Because jdnfbfjd,c,d
Y e s
