He's not ashamed to say that he falls in love with her body first.
It's not entirely that she's so hot she's practically on fire, or that she's got curves that could kill a man if she caught them staring (which is how he learned not to get caught), but its what he learns he can do to her body that no one else can.
There's her hips; dangerous as they rock while she walks, twisting from side to side in a way that gets her all the attention in a room. It's nothing intentional, it's just how she walks and wandering eyes are drawn to it. On a mission its invaluable as a distraction, and she's not afraid to use them for the greater good, but in the training room he knows its just another annoyance that other agents use to prevent themselves from taking her seriously - until she floors them without losing a hair out of place.
But Clint can make those hips roll with a mind of their own…he can make them buck wildly and no one else can do that because she wouldn't let anyone else. She wouldn't let anyone else see how those hipbones of hers have a tendancy to bruise if someone lands a kick there, because there's only one person she'd allow to brush their fingertips over to inspect it and that's him. Hip to hip and everything in between, as far as he's concerned, belongs to him.
Just down from there are the thighs - those could and have choked a man to the brink of death. Whether or not anyone has actually died with their face between her thighs is something she always falls silent at, letting the imagination wonder how soon they'd die of a number of emotions before those muscles cut off their air supply. One day he'll ask her if anyone really has died, but the last time he asked he wasn't in the best of positions and she'd tightened her knees just enough to warn him that he could very well be the first.
But he knows those thighs are as soft as kittens if you know how to handle them. He knows they're tenser after training with a burn in the muscle, but after the hot shower afterwards they're supple and soft. She may wrap them around the necks of her sparring partners, but she wraps them around his waist as he holds her against the wall, and that's the strength in them that he looks forward to most.
Her wrists are steel strong, straight when tensed and God, those fists at the end of them could put you on the ground faster than a building collapsing on you. It's small, weak looking, but her wrists are the small packages that deadly things come in. Everyone's heard the rumours that inside those wrist covers on her field suit are weapons concealing poison, but very few knew that they're really true.
Though at night, they'll curl around each other and she'll always put a hand on his cheek when she tells him those words he'll never beg her to say but always needs to hear when its just the two of them. He knows the skin on her wrists is almost hilariously sensitive but placing his lips there while she cups his face determines whether they'll spend the next hours sleeping or trying to get inside each other's skin.
He falls in love with those dangerous curves, the death grip thights and the hidden strength of her wrists. Not just lust to feel them in other ways, but pure love. Because she doesn't use them to tempt him, and it's gone so far beyond temptation that its borderline ownership, not that they'll ever admit that. He loves those parts of her because she is them. She is the swaying hips as much as she is the bucking ones, she is the tensed thighs as well as the silky ones, and she is the clenched fist as much as the sensitive wrist.
And she's more than that. He falls in love with that body and it becomes more and more each day. He loves how she shuffles her feet a little more on the weekends and that becomes a love of how she only yawns without covering her mouth when she's pouring a coffee. He loves how she flicks her hair to the side in the training ring even if it's pulled back and that becomes a love of how she really spend a lot of time before a mirror getting a mixture of real and enhanced curls. He loves how she can make him do things, react to things, whisper things that he never has before and that becomes a love of how she loves him in return.
He falls in love with her body first. Her mind follows, but only because she hides it until he's too far gone to back away.