If the King of Curses himself takes a liking to you, you only have a few options. You can kill yourself, try to run, or give up. And he's quite happy that you've chosen the easy way. Now he can have you all to himself, in his luxurious palace. He could chain you to his bed and there's nothing you can possibly do to fight him off.
He can cover you in the finest silks, the shiniest jewelry, and the sweetest oils. There's nothing more delightful than the look of fear sparking in your eyes when he gets closer, reaches out a hand, or starts to speak. He loves how you flinch and cower. Such a lovely little mortal. You're so weak. Nothing like the sorcerers he's fought against.
It's a good thing you decided to cave to him, otherwise things could have gone terribly for you.
"You're so very delicate," Sukuna croons to you, scraping his nails lightly across your jaw. He grins when you shiver, baring all his teeth like an animal ready to attack. Which isn't exactly inaccurate. So cute and little. Soft, all syrupy muscle and dermis... He could bite a chunk out of your stomach so easily. Chew, chew, and swallow while he watches the abject horror on your pretty face. He wonders if he could convince you to let him do that. You are so easy to manipulate.
"Come here." He scoops you up and puts you in his lap aggressively. His hands start brushing over your body. Watching your body movements and facial expression closely, he pinches the fat of your thigh. He likes when you flinch and make little noises in pain. He loves when your skin turns red, whether from you blushing or hurting.