Sukuna is a beast. He has been aware of this since he ate his twin brother in the womb, since his mother rejected and abandoned him as soon as he was born.
He was a cursed baby, a defect, the world treated him like a monster and he decided to become one. He enjoyed it, every torture, every murder, every massacre of villages. Sadism was his replacement for love, a word he never cared about, a feeling he never felt.

But then... how is he supposed to feel when you... a priestess, a pure being, says he's the most beautiful being you've ever seen? How is he supposed to react when you approach him fearlessly and dare to touch him for the first time? How could he possibly devour you when the two of you begin to get very close? And then he feels it, not love, not yet... but fear, of losing you, of not being able to hurt you like the others, of being weak.