What McGee noticed was the beer.

After Mexico, the boss had made an effort to be more outgoing, to be more present for his team. They had developed the habit of gathering at Gibbs' house once or twice a month for pizza, beer and movie night. It had been a little odd at first, but had quickly become a time honored tradition with its own rituals, easy and comfortable and fun. Gibbs was still more of a watcher than a participant in the joking around and popcorn fights, but a relaxed and laughing watcher, for the most part. On this particular Friday McGee had set himself a challenge to notice one new thing about each member of the group, so he was being particularly observant. And what he noticed was the beer.
Tony stood up and walked to the kitchen to retrieve another beer for himself - Guinness, as usual. And came back with two, both opened - a Guinness and a good old American Coors. He took a long draw from the Coors, then absently handed it to Gibbs, who took it just as absently, not really looking up. He took a drink without ever looking away from the movie, and Tony stepped over Abby and went back to his seat.
It was shockingly familiar and intimate. McGee was sitting beside Gibbs and never heard him ask for a beer, or say anything to DiNozzo, for that matter. Tony didn't just grab two of what he was drinking, he knew Gibbs' preference, he opened it for him - and took a swallow. You just didn't drink from the beer of someone you weren't intimate with. He felt as if he had witnessed something very private, and very telling.

What Abby noticed was the hair. Tony had walked into the kitchen for more popcorn, and when he returned instead of crossing the room in front of the screen he dropped to the floor in front of Gibbs, and Gibbs spread his knees so that Tony could lean back against the sofa between his thighs. She almost gasped out loud - she was currently curled up on the sofa beside Gibbs and had a perfect view of Tony leaning back, shoulders brushing the inside of Gibbs' thighs on either side.
They sat that way for awhile, and she began to breathe again - maybe it was nothing, DiNozzo had no personal boundaries, after all - then she saw it. Gibbs' large hand had subconsciously reached for Tony's head - not to slap but to caress. He ruffled Tony's hair idly, casually running his fingers through the carefully styled coif - and Tony leaned his head into the Boss's hand like a kitten, for just a second. Yep, it was official. She could die now.

What Ziva noticed was the cooking. It was fall, and DiNozzo was making a pot of his famous chili for movie night. He moved around Gibbs' kitchen effortlessly, never asking where anything was or if Gibbs had cumin - he seemed to know. And they two of them worked together in the kitchen
easily, never getting in the others way, tossing a spoon or the much sought-after grater back and forth. They had done this before, she mused - more than once. McGee and Abby were in the living room setting up for the movie, arguing over the lighting levels, Ducky was sitting at the kitchen table and she was standing beside him, and Tony was lecturing on cilantro as the most divisive of all the herbs when it happened - Gibbs took the spoon from Tony's hand for about the 20th time to taste the chili.
"Mmm", he groaned orgasmically, and Tony raised an eyebrow at him.

"That good?"

"Yup."

And without hesitation, Tony reached out with his thumb, wiped an errant smear of chili off Gibbs' lip, then popped his thumb in his own mouth. " , it's that good," he grinned.
Ziva's eyes met Ducky's, and she was surprised to see more satisfaction than shock in his. He gave an almost imperceptible head shake, and she dropped a single nod. Don't mention it, his eyes silently told her, and she had agreed...for now.

What Ducky noticed was the shirt. It was summer again, and movie night had moved outside for the moment. Gibbs was manning the grill and the 'kids' were spending the last moments of sunshine playing some bizarre game of Frisbee with wacky rules of Abby's creation. They were running and leaping and laughing and Tony was winning, of course, his athletic prowess not subjugated by Abby's nonsensical regulations. He was sweating lightly in the late summer evening, and he abruptly stopped in his tracks and grabbed the edge of his worn Redskins t-shirt. He caught Gibbs eye, then pulled the shirt over his head in one seamless move. He winked lazily at Gibbs, and Ducky heard the Boss' quick intake of breath as Tony stood in the golden sunset, torso flawless and gleaming with sweat. His athletic shorts sat low on his hips, exposing his abs and navel and the trail of dark hair dropping out of site. He was stunning.
"Fuck"...Gibbs growled under his breath. Tony grinned at him and tossed Gibbs his shirt, and Jethro popped up one hand and caught it flawlessly. He rolled his eyes at Tony and mouthed "Behave".
The Frisbee came straight to Tony and he dove back into the game. Gibbs stared after him for moment, then turned his attention back to the grill.
Ducky knew exactly what he had just witnessed. "Jethro," he began.

Gibbs turned, surprised to see the older man standing right behind him. "Don't, Ducky", he said. "Not a word. You have no idea".

"Just - be careful, my friend."

Gibbs laughed humorlessly. "Who are you worried about? Him - or me?"

"Both of you, Jethro. I care very much for both of you, and for the sanctity of the team. If anything should - "

"Don't you think I don't know that, Ducky? Don't you think I don't have this conversation with myself every day? But I haven't felt this alive since - in a long time, Ducky."

His heart broke a little for his old friend. "I can see that, Jethro. I have seen it for a long time, seen the way he makes you feel. I AM happy for you. Just - be careful with him. Don't hurt him. You could break his heart."

"I think it's much more likely that he'll break mine," Gibbs muttered, then busied himself in a flurry of activity, removing food from the grill. Ducky watched him for a moment.

"Then - this isn't just a fling, Jethro? Just a tumble with a hot boy?" Gibbs glared at him over his shoulder. "It's not, is it? Oh myyy. You - love him?"

"God help me - I do, Ducky."

"Does he know?"

"Not yet."

"What are you waiting on?"

"I - I don't know."

"He adores you, Jethro, has done for years."

Gibbs whirled to face him. "Really? For years? You think - "

"Oh, dear boy, I know. We all know how he feels about you, we just never thought you would return it."

A sudden outburst from the yard drew their attention. Abby was riding on McGee's back, shouting "Tony won! DiNozzo dominates!" as they headed back to the patio.

"Looks like your boy is the winner, Jethro", said Ducky. "Perfect timing - dinner is ready, yes?"

"Yep. Come and get it!" Gibbs shouted as his team approached.

Tony leaned close to Gibbs as he passed and whispered "Oh, I intend to," and grabbed his shirt from the railing with a smirk. Gibbs rolled his eyes and Ducky raised an eyebrow.

"Good luck, my boy - to both of you."