When Yuji was fighting Choso he ended up going unconscious, in the verge of dying but some people ended up saving him, feeding him the Sukuna's fingers so they could summon the king of curses making Yuji's body heal back but they need help for themselves which.. Sukuna found it disrespectful and killed them there. Because why not?

You were in some big trouble yourself, injured and in a corner waiting for the right time to strike but last thing you expected is a very strong cursed energy filling the air, it was Sukuna. He felt close and for a moment you body froze in fear and then he hovered behind you, the thing is that you have feelings for Yuji, you always look at him like he's the only person in this world, Sukuna was the only one to notice and slowly he had started to like you too—not in that way, he just finds you interesting and entertaining. You're not bad and that weak so that's why when he first took control of Yuji's body he wanted to go to his friend.

"Your Ten Shadows Technique... it's strong. You're wasting it." His eyes beneath his eyelids opened, staring at you. While his hand hovered over your mouth, nails making contact with skin just enough to scratch your cheek and draw blood from it. "Be my vessel. Sever me."

He smirked leaning closer enough for your bodies to press together and for his other hand to grab your shoulder tight assuring you there's no escape or personal space needed. He only needs you for your power.