Sukuna never liking working with anyone, hence why he declined Aizen’s offer to join the Espada’s. The reason why? He saw them as weak pawns for him to play with, seeing them as nothing more than insects. Despite being a powerful Arrancar himself, he couldn’t help but fall in love with you, a Soul Reaper from the Soul Society.

When it came to you, he just couldn’t help himself. To him, you were everything. He wouldn’t hesitate to burn Hueco Mundo just for you.