Athor's note: Hello everyone! I am so proud of how this story is doing! People really seem to like it, and I've gotten a lot of positive comments and writing tips. I just want to thank everyone who liked or followed my story, or left a comment. It makes this all the more fulfilling. Anyway, I'll let you guys get to the story, things begin to get serious here. So please enjoy the next chapter, and happy holidays!

It had been a few hours since Donnie stormed off in a fit and Leo was beginning to worry. They had managed to settle Raph down enough to check his nose, it was bleeding but, thankfully, not broken. After some pestering from Leo, Casey had finally told the story of what had caused Donnie to be pushed over the edge. Leo did his own explanation as well to the two humans. He told how Donnie had fits very often when he was younger, but these violent fits had lessened over time. Instead, Donnie took all his anger and frustration, and used it to make his many wonderful inventions. Every so often, something would push Donnie over the edge, but he would quickly fix his mistake.

At the moment, Leo was walking through one of the many underground tunnels in search of his third brother.

"Donnie!" The expanse of cement caused his voice to echo almost ominously.

"Donnie!" Once again, Leo called out to his brother, only to be answered by silence. The soft slap of his feet on the ground was the only sound, except for his occasional call for Donatello.

"Donnie! Stop playing games and come out. Everyone's worried about you. Especially April." Seconds ticked by in silence. Soon they turned into minutes, and those minutes seemed to drag on for hours in silence.

"Darn, I really thought that would work. He must really be upset if he doesn't come running at April's name." Leo chuckled to himself as he continued in his search. Many minutes passed as Leo pressed onward, walking past the many familiar tunnels. Occasionally, he called out his brother's name, only o be met with the dripping of water, or the squeaking of rats. As the minutes dragged on to half, one hour, one and a half, Leo became more and more agitated and panicked.

"Donnie?" A frantic pleas echoed through the silent tunnels. "Donnie, I swear, if you're playing some kind of joke, I will make you do nothing but katas for a week!" The empty threat only seemed to silence the tunnels further, and Leo finally began to realize that this was no joke. In a panic, he began to race through the sewer tunnels.

The silence was deafening as Leo ran. Not even the thud of his large feet seemed to make a noise. He called out his brother's name incessantly, looking through every room, nook and cranny in desperation. How could he lose his brother? It was his job to watch after them, protect them.

By the time Leo had reached the lair, he was screaming for his little brother. The others dashed out to meet him, alerted to his panic by his screaming.

"Leo, what's wrong? Where's Donnie?" April grabbed hold of Leo's arms, and he stared at her with wide eyes.

"I-I can't find him anywhere! H-he's gone. Donnie's missing!"