Mitsu is a character from the third live action movie, Turtles in Time. Mike had a huge crush on her, and when they had to go back to the present, he was so forlorn he declared to Splinter, "I'll never laugh again." What you read below is actually what Splinter did in response to that.
"I thought a lot about what you said," Mike told him as he approached. He slowed his pace, and then sat down beside him. "About… everything. About Donnie treating me like he does. And about… how he used to be. And I thought, maybe I was wrong. Maybe he can come back. But…"
"Mikey, something tells me beating him up isn't the best way to go about getting his sense of humor back," Leo said dryly. Mike snorted softly.
"Back when… when I had to leave Mitsu, I really thought my sense of humor was gone. I know you guys think I was being melodramatic, but it's true. It was like someone had cut it out of me. I really didn't think anything would be funny, ever again. And then," he chuckled wetly, and Leo was aware of tears that weren't being shed, "then sensei put that lampshade on his head, and it wasn't even that funny, except it was, and I laughed. And then, after that, I found another thing to laugh at, and another, and then eventually, it was like I got my sense of humor back. And I just," he said, sighing, "don't know how to do that for Donnie."
Leo was silent for a moment.
"You could try the lampshade," he said. Mike gave him a scornful look that was nonetheless tinged with amusement. He sighed as well. "Mike, I think you might have been right. This is who Donnie is now. And that doesn't mean you can't try to help him get a sense of humor (boy does he need one) but I don't think…" He didn't want to say it. "I don't think the old Donnie is coming back."
Michelangelo was silent for so long Leo was afraid he'd said the wrong thing.
"Do you think I'm being childish?" he asked eventually, his voice small. "That's what Donnie said. That I should grow up. Do you… do you think…"
Leo flung an arm around his brother's shoulders.
"Mikey, you're the only one of us who has managed to live through the things we've lived through without getting hardened and jaded. I think that's amazing. And I wouldn't change it for anything. Even if I can't be like that, it's nice to know you can. No, it's essential. It might be unfair to you, but the day you become as jaded as the rest of us will be a sad day for me."
Mikey nudged him playfully, and Leo could see his smile.
Raph hated this stuff. Donnie was rubbing his throat absently as he crawled forward for his staff. Raph knew he could easily pick it up and hand it to his brother, and that might count for something, but this situation needed more. He just didn't know what the heck that was.
"I'm sure Mike don't really hate you," he said. Where had that come from? And it was clearly not the right thing, because as Donnie stood with the help of his staff he gave him a dark look.
"He never said he hated me," he told him. Raph blinked.
"Oh. Well, then he doesn't." Don rolled his eyes and moved to walk away. "He does miss you, though."
Don stopped.
"What does that mean?"
Raph was asking himself that same question. He thought about it, and then realized his mouth had been right.
"When Leo left, and you tried to be him, well… it was like you left too. And Leo came back but… you didn't."
And that still didn't seem to be the right thing to say because Donnie was looking at him downright angrily now.
"You mean the sacrifices I had to make to keep this family intact? Is that what you're referring to? Because correct me if I'm wrong, but I didn't exactly notice you and Mikey stepping up to help fill the gap."
Raph flung his hands in the air.
"You know, maybe the ones who needed Leo's trip were us. Because it's freaking pathetic that we apparently can't handle ourselves while he's not here."
"Don't talk to me that way, Raph. I had just about enough of that when Leo was gone. I don't need it now that he's back."
"That's just it, Don. Leo's back. You don't have to pretend to be him anymore."
Don jabbed his bo into Raph's chest.
"I am not pretending to be him. This is who I am now, and if you guys can't handle that, then fine. I'll just hole myself up in the lab and you can have all the fun you want without me."
"But it won't be fun without you Don." And now Raph knew he'd lost it, because something that sappy should never come out of his mouth. Don looked at him, confusion warring with concern on his face. Raph waved him off. "Least, that's the way Mikey sees it," he said, thinking, nice save.
"Mikey needs to grow up," Don muttered, and Raph turned back to him.
"Does he really? Do you really want some mature version of Mike walking around? Because I sure don't. That sounds," he shuddered, only partly for effect, "creepy."
"Do you really want Mike to act like a child for the rest of his life?"
Raph stared at his brother, really looked at him. There were deep circles under his eyes that his mask couldn't hide, and he looked exhausted.
"Mikey doesn't act like a child. Not all the time. Not when it's important. That," he jabbed a hand at the wall where until recently Donnie had been pinned, "that seem childish to you?"
Don was silent. Raph went on, trying desperately to throw out as many words as he could, hoping at least one would hit the target.
"We need Mikey being funny, Donnie. Leo's Mister Trained Master, I'm on a short fuse, and you… well, anyway, we need to laugh. We need Mikey there taking our minds off stuff." Don groaned, turning away.
"Not you too." His posture sagged. "Mike was saying the same thing, but do none of you see how idiotic that is? We're a team of ninjas, Raph. We need a class clown like we need a hole in the head."
"We're also brothers, Donnie, or have you forgotten that? And right now you are being nothing but a jerkwad to your brother."
"I'm a jerkwad, huh?" Don muttered. "Come on Raph, tell me how you really feel."
"I just tell it like it is, Don."
"Is that what you call it? Because I call it assholery."
"That's not a word!"
Donnie made a noise like he was giving up on the whole world and turned to go. Raph cursed his big mouth. But then he thought of something and decided to let it spill one more thing.
"We… we all miss you, bro."
Donnie's steps did not falter, and Raph wasn't sure he'd heard him.
