The thunder boomed overhead, the sound bouncing off the pipes and echoing through the sewers.

Donnie sighed and rolled over in his bed, picking up his pillow and sandwiching his head in between it and the mattress. He knew he wouldn't be getting any sleep tonight – the sewers always seemed to be able to make the sounds of the thunder twice as loud even though they were farther away.

Donnie growled as the sky clapped again and gave up on blocking it out, putting the pillow back under his head. Donnie had never been scared of thunder – even when they were kids. He'd had the rationality to realise that a mere sound couldn't hurt them. It might be scary, but Donnie had used science to get past the initial fear of the loud noise.

It almost sounded unnatural. It didn't seem right that something as beautiful as nature could produce something as evil and as ugly sounding as thunder, although, he supposed, there were far more ugly things in the world.

Through the years, Donnie had managed to convince his brothers about the concept of thunder, and one by one they had eventually stopped having a fear of the sound. That is, except for Mikey.

Mikey got the concept that it couldn't hurt him just fine – Donnie knew that. However, the knowledge did nothing to settle his younger brother's fear; Donnie had long since given up on trying to cure Mikey, instead trading science for a spot in his bed.

Although Donnie would never say this out loud, he was pleased his brother always went to him for reassurance during thunder storms. Mikey always went to Leo for guidance, and he hung out with Raph the most in his spare time. It made Donnie feel special, like he held a place in Mikey's heart that the other two brothers couldn't fill.

During the day, his younger brother would be cracking jokes, laughing and making the most of everything. He would fight well, rarely show any true fear and would take every chance he got to annoy his brothers. However, during the night Mikey seemed younger, more vulnerable. Maybe it was because he was tired, maybe it was because Donnie himself was tired, but to him his brother seemed...smaller at night. Like he needed protecting.

A knock at the door swept Donnie from his thoughts and he lifted the covers off of him, knowing exactly who it was. He manoeuvred through his room, stepping over the unfinished projects which littered the floor before he made it to the door. He opened it and smiled down at his younger brother, who was looking up at him with wide eyes.

"Hey, Mikey." said Donnie, opening the door wider. Mikey took this as an invitation and stepped in as Donnie closed the door behind him.

"Thanks." Mikey looked at the ground and shuffled his feet, obviously embarrassed at the situation.

"Is it the storm?" asked Donnie, as he rested a hand on his brother's shoulder to guide him to the bed.

"Yeah," replied Mikey quietly. As if it was backing up his point, the thunder boomed and the young turtle jumped, looking around with wide eyes before blushing and returning his gaze to his feet.

"You know, there's nothing to be ashamed of," said Donnie as they sat on the bed. "Everyone gets scared once in a while."

"But you guys grew out of this years ago!" protested Mikey. "And I'm still a wimp..."

"Hey," said Donnie, placing his hand on Mikey's shoulder. "You're not a wimp."

"I am," said Mikey, keeping his gaze fixated on the floor. "How many fifteen year olds do you know who are scared of thunder?"

"One," said Donnie gently, and Mikey sighed sadly. "But I only know three altogether,"

Mikey gave a quiet chuckle, "Yeah, I guess."

"Look Mikey, everyone gets scared – it's nothing to be ashamed of,"

"But we're meant to be fearless!" protested Mikey, looking up at his brother. "We're ninjas, and I don't see you guys looking for comfort in the middle of the night."

"We're scared of other things," said Donnie. "Have you seen the way Raph gets when he sees a bug?"

Mikey giggled and sniffed, "yeah, he totally freaks out!"

Donnie wrapped his arm around Mikey's shoulders and gave him a small squeeze, "My point is, being afraid doesn't make you a wimp, or any less of a ninja. It just makes you human. Or...you know...mutant."

Mikey sighed, "Thanks, Donnie."

"No problem Mikey." Donnie scooted back in the bed and lay down, leaving enough room beside him for Mikey to lie down too.

"Hey, Donnie?" asked Mikey as his head hit the pillow.

"Yeah?"

He hesitated, "Can you...not tell the others about this? I kinda don't want them finding out. Especially Raph."

"Our secret," promised Donnie, pulling the covers up over both of them.

Mikey yawned, setting his brother off too. "Night, Donnie."

"Night Mikey."

Thirty seconds later, they were both asleep.