He's immortal and powerful and a killer and former royalty and more than a little spoiled and pompous and blustering and he would catch fire in the sun but a bullet wouldn't even phase him and he flinches at the name of your mother's God.
But he needs you to hold his hand every morning and night and he needs you to brush his hair and tell him he's cool and he tells you goodnight and trusts you in a room where there are windows. He makes a portrait of the two of you together forever and he says he's sorry when he accidentally hurts your feelings and he gets so flustered the first time he calls you "friend" that he tells you to forget it (but you don't you never will you hold that memory in your hands like a mug of warm cocoa).
He offers himself up to die to protect you and he asks you to stay until he falls asleep because he's a little bit scared and he keeps your secrets and he defends your honor and he giggles with you and plays chess with you and tells stupid jokes just to eagerly await your laughter. He asks you about grief and he asks you about belonging and he asks you to see the world on his arm and then he asks you to watch him marry someone else.
He asks too much from you, quite often, but he doesn't know what he would do without you. He smiles at you on his wedding night like he wishes you were the bride. He takes the one thing you found for yourself and when you ask him why, he just looks sad. He lets go of what makes him happy with tears in his eyes, because he can't stand to see you so miserable. He thinks he forgot your birthday and gets you a present. (It isn't your birthday, but you love it anyway. Every night you fall asleep surrounded by evidence that he cares.) He does ridiculous things to impress you, to make you jealous, to make you notice. (You notice, of course you do, how could you not?)
He begs for you. He cries for you. He says he knows you better than anyone. (He's right. He does.)
He never imagined you would betray him. When you do, he looks at you like you've broken his heart. When the time comes at last for him to kill you, he draws your weapon to dig into his own throat.
He forgives you. He forgives you. He forgives you. He forgives you.
He takes you home and fixes your problems and fixes them again and kills for you and dies inside at the thought of losing you someday. He doesn't tell you that.
He's ancient and he's stubborn and he only ever relents for one person, and that person is you.
(You followed him home over a decade ago and every time you leave, he goes a little mad. Every time you leave he falls to pieces. Every time you return he pretends he was fine without you.)
But when it's time for bed, he still needs you to stand at his back and speak softly in his ear and brush his hair.
