Apart from assassinating people, Ezio spends a lot of his time chasing after and seducing women. What if the reason for this excessive womanizing is because he is, at the very least, bisexual? He was attracted to men throughout his life and tried desperately to forget it and to convince himself that there's no such thing. Unfortunately, meeting Leonardo only complicates matters for him, because he's immediately attracted to the artist and over the years his feelings turn into full blown obsession which he struggles against by sleeping with various women and killing people. Only in the end something happens and he snaps, bending Leonardo over his table (or anywhere else, I don't have a preference) and has his way with him. Could be consensual or non-consensual, but he'd definitely be horrified and ashamed in the end. Bonus points of Leonardo tries to comfort him afterwards.