Disclaimer: I, unfortunately, do not own NCIS.

Abby looked up when she heard the "ding" of the elevator and saw Tim McGee step out. Actually, "step" is an understatement: he huffed off. "Problem, Timmy?" she asked as she looked back into the microscope.

McGee didn't respond, opting instead to plop down in a chair nearby, his back to Abby. He began typing, his fingers striking the keys aggressively as if each of them had somehow wronged him. "McGee, stop brooding and tell me what's the matter."

"Nothing is wrong, Abby," he said, still not looking at her. "I need to pull up Henry Mason's phone records to see if he had been in contact with Lieutenant Anderson recently."

"And is there a specific reason you couldn't do that on your computer upstairs?" She asked, abandoning her microscope for the time being and coming up behind him. When he didn't reply she grabbed the back of his chair and turned it around so that he was facing her. "Come on McGee, you're pouting more than usual." At this his lower lip jutted out more. "What, is Tony giving you a hard time?"

"Is he ever giving me an easy time?" he retorted with a mirthless smile. "It's nothing," he asserted, "just Tony being immature." He attempted to turn the chair back around, but Abby stood her ground. Her eyes stared into Tim's, her mouth set in determination. Tim did his best to match the glare of her eyes, but after only a few seconds she had won the staring match. "Fine, I'll tell you!" he grumbled. "This morning I accidentally spilled some water on my pants. It was on my…well…groin area," he said, his cheeks reddening a bit, "so it looked a little bit like I had…you know," he trailed off, his face even redder. "So Tony has been calling me 'McPeePee' all day."

Abby looked at him for a moment, her eyes gleaming and her body shaking with laughter she was trying to hold in. Finally, she couldn't stand it any longer and she threw her head back, howling with laughter. "That is hilarious, McGee!" she said, wiping tears from her eyes. She noticed Tim slunk down lower in his seat. "Come on, McGee, you have to admit it's pretty funny."

The right corner of his mouth twitched and Abby could the small trace of a smile. "Yeah, I guess it's a little bit funny," he conceded, "but he's been running it into the ground." Any trace of a smile was long gone now. "We went to interview the witnesses and one of them was this very cute girl. She and I started talking and I thought maybe we were kind of flirting. Suddenly, DiNozzo pops up and says, 'Hey, McPeePee, if you have the urge to relieve yourself I'd rather you use that bush over there and not get it all over your pants again, cause if you do urine trouble.' He did it just to embarrass me in front of her, too!" Tim swirled the chair back around the face the computer, still determined to continue pouting. "I just don't understand why he's always teasing me."

Abby pulled up a chair next to Tim and slid into it. "Oh, come on, McGee," she said, rolling her eyes, "you really don't know?"

"Because he's got nothing better to do, I guess," Tim muttered.

Abby shook her head. "McGee, how much older are you than your sister?"

Tim furrowed his brow, not understanding where Abby was going with her question. "Uh…about eight years," he said.

"And as long as you can remember, have you ever teased her or called her names?"

Tim paused for a moment, his mind going back through Sarah's life. "Well yeah…I mean, I teased her about as much as any older brother does." Seeing the smile on Abby's face, he added, "But that's different! I mean, I never called her something like McPeePee!"

"Probably because you never got the chance to!"

"Well, that and I don't think I would have come up with it," Tim added with a sheepish smile. "But she could be such a brat sometimes, too. I mean, if I did the slightest thing she'd go crying to mom about it."

"Kind of the way you go around pouting every time Tony teases you about something." It wasn't a question, but the statement of a fact.

"I do not pout," Tim claimed, his lower lip jutting out yet again. "Besides, we're adults here so Tony should know better. I was a pre-teen when I teased my sister." Abby gave him a skeptical look, one eyebrow raised. "Okay, so I still tease her sometimes," he admitted. "But I still care about her."

Abby smiled. "No one is saying you don't, McGee, but we tease people we care about sometimes. Hasn't Tony been there for you when you've needed him?"

Tim thought back to when he almost set off the bomb Ari had set in the trunk of the car. Tony had seen it, though only by luck. Still, Tony had taken control, insisting that Tim and Kate run ahead, that he would catch up. Tim thought about when he had finally worked up the courage to go down to autopsy and see Kate. Tony had come down and given him the support that he needed. When Tim was distraught over killing Benedict, Tony had come over to cheer him up, Sure, Tony had gone about it in the wrong way, but in his heart he had meant well.

Abby's voice broke into his thoughts. "Tony's an only child, McGee. He doesn't know what it's like to have siblings, so in a way the team is his family. You're like the little brother he never had. He's going to treat you the way any older sibling treats a younger sibling. Problem is you're so used to being the older sibling, you don't know how to react to being on the other side."

Tim considered this, considered everything Abby had just said. He and Sarah had been at ends with each other growing up (what siblings aren't?). He had teased her, called her names, and, on occasion, even gone out of his way to embarrass her in front of her friends. Still, when push came to shove he had been there for her as only a big brother could be. Who else would have put their job at risk to protect her when she was suspected of murder?

Tim gave Abby a small smile. "Thanks, Abby." He was rewarded with a trademark Abby hug.

"Hey, SpongeBob PeePants!" Tony called out gleefully to Tim as he sat down at his desk. "Glad to see you've finally returned!"

McGee simply smiled. "You can tease me all you want, DiNozzo. I'm used to it by now."

"Tease?" Tony asked with a look of mock surprise. "Who said anything about teasing you? I'm simply admiring how cool you are," he explained, trying to look as innocent as possible. When Tim looked at him with puzzlement, Tony said in his best Adam Sandler voice, "McGee, you ain't cool unless you pee your pants!" He let out a small squeak as a hand smacked the back of his head. "I deserved that one, boss."

Tim snickered quietly to himself. He'd have to ask Tony to come up with some good names for him to call Sarah the next time he saw her.

AN: This one-shot is dedicated to my older brother who is a pain in the ass (and whom I love dearly).