They enter her apartment and head right over to her room, Kate knows what he needs. Sometimes he needs reassurance, he has doubts about how much into this relationship she is and she can't blame him, she has run several times from him before so they found a way to reassure him. It was never spoken, nor agreed on, it just happened one time, and then the next time it happened again and now it's the way she tells him how much into this she is. It started with a jealousy rage and she realized she wasn't the only one with insecurities.
She has only ever done this for him, and he knows it. Kate is always in control, the dominant one in any relationship, so she gives it up for him, lets him be the dominant but only when he needs it, because she likes it, and it reassures her too, makes her know how much he needs her. So she gives him this; he takes her, makes her his in any way possible.
They enter her room and immediately he's on her. He pushes her against the wall, her back to him, rips her shirt open, and every time she has the same response, she's breathless and grinding her ass on his erection. He pushes her roughly against the wall and releases her breasts, thankful that it's a front clasp bra so he doesn't have to take it off. He loves seeing her half naked and exposed.
His hand is already down the front of her pants, fingers half rubbing her and half being ground on, his other hand squeezing her breast roughly. He bites on her shoulder blade through her shirt and checks for her wetness. She's covered with her juices so he shoves three fingers inside of her, eliciting a loud groan from her "Castle".
He takes his hands off of her and quickly rids himself of his clothes pushing her on the bed. He doesn't have to say anything, she already knows the grill. She gets on her fours and he slides her pants and underwear down her legs, lifts them and lets the pants bundled over her ankles, restricting her movements.
Her ass is in the air, her back covered by her shirt and breasts hanging on her naked chest, she stays still, waiting for him, but opens up her legs a little to give him more access while he lathers his hard member with the lube she keeps for him. He kneels behind her and pushes her to lay her front on the bed, her legs opened at a weird angle since her ankles are still constricted. He parts her cheeks, positions himself on her opening and thrusts into it at once.
"Arrggh" She lets out a throaty groan at the intrusion and he sneaks his hands to her front, one roughly squeezing a breast and nipple while the other plays with her center. He feels her body softening and she starts wiggling her ass, urging him to go on. She's ready now.
His thrusts start long and slow and his hands are still on her front, her pants and moans muffled by the pillow she's biting and her hands holding the headboard, eyes squeezed shut. He thrusts hard into her ass once, twice, and a third time and feels her body trembling on his hands, he moves his mouth to her neck, nibbling on her skin as he shoves his fingers into her and she convulses around him, muscles tightening and releasing.
"Mine" he growled on her ear as she was coming down. She goes limp on his arms and he drives himself into her again, faster, harder, crushing her to him.
"Yours" she lets out breathless. She can't take the amount of sensations on her body, her still very sensitive skin tingling from his touch, her throbbing core being pushed against his palm, his fingers still dancing inside of her, the rough ministrations to her breasts, and his weight over her... He drives himself harder into her, ready to finish and she feels herself convulsing again.
"Mine, Kate" he repeats as he comes inside of her, and she feels the need to tell him, to appease him in every way possible because he does the same with her, when she's jealous and insecure and wants nothing more than to run away from all of it, he comes through.
"I belong to you now", she says. And she's never wanted to before, never wanted to belong to someone, to be called theirs, but she needs him too, so much that she can't not see him by her side, forever.
He's still inside of her, soft now, his fingers are still inside of her, and his hand still cupping her, but now he lays on his side holding her to him and positions her so he doesn't come out of her, back to front, legs to legs.
"Mine" he says, and this time, she hears relief in his voice. But she knows he's not completely soothed, so she says what she's said every time he's needed this kind of reassurance before, and then, they'll fall asleep like they have every other time.
"Always".