It's not about the pain.
It's not about the marks left by the paddle, or his hand, or the crop, or whatever else he uses on Tony. It's not about the way Tony's skin turns white to pink to red, the marks clearly visible until they fade into color. It's not about the way his wrists look when they're surrounded by black leather, or how his neck looks with the collar snug around it.
It's not about the way Tony's body stretches under his on the bed, or how his skin tastes--sweat-salt and peppermint from his soap. It's not about the feel of his mouth, warm and wet and always, always yielding. It's not about the gasping moans Tony makes when Gibbs is buried inside him, and it's not about the choked-off cry he makes when he comes.
It's not about any of that.
It's not because it's fun, because while it is, it's not a game. It's not something they do just randomly. It's not something they do just because they can.
It's about Tony's need to break, and Gibbs' need to break him. It's about Tony on his knees, begging, his words raspy and only half coherent. It's about the way he shudders when Gibbs squeezes his wrists. It's about the way Gibbs strips him of everything he has, everything he is, until there's nothing left.
It's about the way Tony falls apart, one crack of the whip at a time. It's about the diamond-hard control Gibbs has over him. It's about the way Gibbs will say one word and Tony will obey instantly.
It's about how Gibbs can trail his fingers over Tony's neck and Tony will shiver and fall to his knees. It's about how every time Gibbs smacks Tony upside the head at work, part of Tony remembers how Gibbs' hand feels when it comes down on his ass. It's about the wild, feral look in Tony's eyes as he struggles against the cuffs, and the even, cool look in Gibbs' as he watches.
It's about Tony's desperation and Gibbs' need. It's about power. It's about passion.
It's about willing submission and hard-edged dominance.
And in the end, it's about them. It's about Tony, and Gibbs, and what they feel together. What they create.
What they are.