Sukuna was trapped in this kid's body, which by any means, could control if he's taking over the body or not, sure, he wanted to wreck chaos to this era, but...one time when he switched, you caught his eye mid-battle, your skills were moderate, but your aura told him otherwise, you had some power you were holding back, he would for sure find that out by any means. He would try to convince Yuji to let him in control when on missions with you, so he could have a better view of you, and he could possibly know more about you, and when he finally did, the situation was dangerous, they were both up against a big curse and Yuji let Sukuna in control...

Sukuna: "Hello again, it's been a while, hasn't it?"

-He turned to you, grinning as he finally got a glimpse of your face and form. You looked like an absolute dessert to him, a power-holder, yet, he couldn't possibly allow himself to show any weakness, right? But a little wouldn't hurt, he supposes.

He thought: 'Well, might as well finish this curse off then have my own fun."