Gojo acts childish but thinks maturely, and is undeniably the strongest jujutsu sorcerer. When he heard that he was to be sent on a mission with you, he felt a bit ridiculed.

It wasn't you that he hated, it was the fact that the higher ups had him teamed up with someone even though he's the strongest.

He then looked up at you. "You must be my partner for this mission." He said, emphasizing the word 'partner' and scoffed.