Disclaimer: I don't own the TMNT or related characters. So basically if there is a character in this story I don't own it. I make no money from this, so please don't sue!
"Master Splinter, what is this?" A little Michelangelo asked holding up a small object for his father to see. The object consisted of two small disks with a long string that wound up on an axle between them.
"It is a yoyo, my son, a toy." Splinter continued to search the dumpster for useful items. Tonight was Michelangelo's turn to come up to the surface. As much as he hated the idea of his sons roaming the streets the fact of the matter was that one day they would have to. So as part of their training he started to bring them, one at a time, up to the surface with him. He had once made the mistake of bringing all four to the surface at the same time and that trip had nearly ended in disaster. He would try again when they were older, but for now it was only one at a time.
"Can I keep it?" The young turtle asked.
Splinter had lost himself in his thoughts, and while he knew where his son was he did not know what he was talking about. Looking around he spotted the yoyo in the child's hands. Seeing no harm in letting Michelangelo have a yoyo Splinter consented, and he had to laugh as the child excitedly tucked the precious item into his belt. While he himself had never used a yoyo Splinter knew the idea behind them and had no doubt that Michelangelo, or one of his brothers, would figure out how to use the small toy in no time.
Over the course of the next few days Michelangelo was seldom without his yoyo. He took it everywhere and Splinter wasn't terribly surprised to see it on the boy's pillow in the evenings.
The young turtle still had yet to figure out how to get the yoyo to come back, but he certainly hadn't given up on it just yet, which is why he was surprised to find another of his sons playing with it one morning.
"Donatello, does you brother know you have that?"
The turtle looked up at his sensei and father startled at his sudden presence, and Splinter felt a slight twinge of guilt for scaring his quiet son like that. It couldn't be helped though, he continued to hope that the child would notice him coming before he spoke. So far Leonardo was the only one who could occasionally recognize Splinter's presence behind him, but Michelangelo and Raphael handled Splinter's sudden presence better than Donatello did. Too busy jumping at his father's entrance the little turtle had not heard the question and sat there staring up at Splinter. Finally, the rat had to repeat the question.
"Does Michelangelo know that you have his yoyo?"
"Yes." The little turtle finally responded. "He's taking a shower. He said I could play with it until he got out. I'm aspposed to keep it away from Raphy. And it never really comes back up so does that make it just a yo?"
"Supposed, Donatello," Splinter corrected absently.
"Sup-posed," the turtle repeated dutifully.
"It might take some time, but I have no doubt that one of you four will find a way to make the yoyo come back up."
Splinter had to laugh at the memory of the last time Raphael had gotten his hands on the yoyo. He couldn't get it to come back and the toy had been thrown across the room. It now sported a good sized dent in one side as a result of the little episode, and evidently Donatello was supposed to guard the object until Michelangelo was done in the shower. Leaving the room Splinter idly wondered what had made Michelangelo choose this brother to guard the yoyo. The one he thought of as his youngest turtle was notorious for having, and hiding, ulterior motives. It might be…
Splinter turned back around to the turtle currently playing with the toy just in time to see the yoyo drop to the floor…and roll back up the string a couple of inches before returning to its natural state at the bottom of the string. Splinter realized that he had just found Mikey's motive, and that the child's bet had probably just paid off.
"Here, Mikey." Donatello returned the yoyo to its owner as promised.
"Did you get it?"
"It came back up a little bit. Not all the way though."
"What'd you do! What'd you do! What'd you do?" Mikey begged excitedly, grabbing his brother by the shoulders and shaking him a little.
"Just pulled up when it got to the bottom!" Donnie cried out, a little fear voice as he explained as hastily as he could and tried to worm his way out of Mikey's grip.
Splinter heard the confrontation and was just about to see what was going on when Donatello shot out of the room almost bowling him over. He sidestepped to avoid the green bullet and continued into the room.
"Michelangelo, was that really necessary?"
"Huh?" Mikey looked up and spotted Master Splinter standing there. "Donnie made it come back up a little!" The turtle shouted happily.
"Is that why he just raced out of here?"
"I don't know. He told me how he did it then ran away. I was kind of hoping that he'd show me." Mikey said a little dejectedly.
"Maybe you shouldn't have shouted at him like that then." Splinter suggested softly.
"I shouted? I'm sorry, Sensei." The little turtle bowed his head.
"It is not me that you need to apologize to." Splinter went back out the door.
The turtle looked down at the yoyo in his hand then out the door through which both his brother and father had departed. Michelangelo decided not to follow for now, he usually didn't find Donnie anyway. Mikey was pretty good at hiding, but he wasn't so great on the seeking front. Instead he tried to do what his brother had told him. Wait until it gets to the bottom? Mikey hadn't thought of that before. He let the yoyo fall to the full length of the string before pulling upward. The double disk popped up a few inches before going back to the bottom of the string. Mikey beamed and tried again. The disk dropped, this time he pulled up a little harder. The double disk crawled farther up the string, but still didn't come all the way back to his hand. One more time the yoyo went down, this time when it reached the bottom Mikey pulled up with everything he had.
The yoyo did not crawl back up the string. This time the yoyo openly rebelled. It shot upward over Mikey's head and continued its way backward. Mikey heard a clonk that he had never associated with the yoyo before, but the next thing he heard was most definitely associated with pain, some of it his own.
"Ouch! What was that for!"
"Oops, sorry Raphy," Mikey apologized quickly.
"What're you doing!" Raphael shouted.
"I was playing with my yoyo, I'm really sorry Raphy. I didn't know you were there. It wasn't on purpose!"
"It better not have been! Want to see how this yoyo handles another trip to the wall!"
"No! Raphy, please no. I'm sorry!" Mikey hid the yoyo behind his back as he moved away from his brother.
Raphael glared at his brother, but in the end left him be. He stomped out of the room rubbing his head where he had been clocked by the errant yoyo.
Within hours Michelangelo had mastered the art of making the yoyo go up and down. A few days later he discovered that if he flipped it down correctly it would spin at the bottom. A quick jerk would have it snapping back up to his hand. That little breakthrough led to a whole world of things he could do with the yoyo. It was him spinning the toy around his head one day before it snapping back to his hands that gave Splinter an idea. While the four young turtles had used several weapons in the dojo, the one that seemed like it might just be the best fit for Michelangelo had not been one of them. That was a situation that he would have to remedy.
Raphael found the things frustrating beyond belief; they just wouldn't go the direction he wanted them to go. Leonardo dealt with them ok, but he was wary of the strange, floppy weapons and Donatello had nearly knocked himself out with them and probably had a concussion, but Michelangelo was a natural. He had already learned how the yoyo reacted to pulls in different directions and he deftly applied that knowledge to the short chain. From that day forward, if given a choice, Michelangelo always picked the same weapon: the nunchucks.