He'll never tell Tony, but Gibbs loves the moments when Tony's face hardens with resolve and he resists, fights back.
Gibbs likes strength and he nurtures it in Tony, in his own way.
But he likes it more when Tony bites his lip, murmurs, 'Yes, boss' and his gaze falls, just for a moment.
Likes that subtly trained submission too much, if he's honest.
He wants to reward Tony for it. He knows what Tony craves and he can provide it.
There's a rule that says he can't.
Gibbs is getting older.
Maybe it's time to wear purple and red.