There weren't many things that really bothered Leonardo, but being stared at was right up there with excessive laziness and poor personal hygeine, and at that exact moment he was being bombarded by both. He and his brothers were winding down from a sparring session by stretching, and Michelangelo, somehow able to sweat buckets more than any of them, was sitting so close their arms were smushed together. To make matters worse, he was also intensely staring at him, something he'd been doing for close to an hour now.
Leonardo huffed irritably and leaned away from his brother, raking a hand down his face, just in case something embarrassing was there. He couldn't understand what all the staring was about; he'd even checked his mask during their break. Nothing.
Michelangelo was humming away, finishing up his leg stretches, and soon back to staring. Leonardo glanced over at his other two siblings, who seemed oblivious to what was going on. His father also seemed not to notice.
"Mike, knock it off, will you?"
"Knock what off?"
"You know what. You've been staring at me going on an hour now. It's not funny."
"No idea what you're talking about, bro 'o mine." Those irritatingly large blue eyes seemed to smile.
"Master Splinter!" he cried as his master was walking past. If Michelangelo was going to be a baby about it, then so be it. Their Master would set him straight. "Mikey's won't stop staring at me."
"Leonardo," Splinter replied without missing a beat, "you are twenty three years old, and you are not unaccustomed to your brother or his peculiar antics."
"But Master-"
Splinter raised a hand to silence him. "As Raphael would say, 'deal with it.' Now, if you'll excuse me, my stories are on."
Leonardo looked on, awestruck, as Splinter eagerly left the dojo, and Raphael and Donatello burst into laughter.
"Dude. You just got told by Splinter."
"...Shut up. And stop staring at me, already!"