"I can see you haven't been skipping out on your training. Is your sharingan up to it's 3rd tomoe? Hows your mangekyo developing?"

A nerd to the very end despite their perverted relationship Izuku was fascinated by the sharingan and wanted to know everything about it and he made the perfect training partner for an Uchiha since OFAs nature would negate genjutsu placed on him.