Hellsing's Alucard and anyone does not do it for me as he is far too removed from humanity imho. Though he might well fuck someone just to fuck with their minds so to speak . Seras on the other hand is still trying to cling to her humanity. Evangelion Kaji Shinji not that impossible Kaji is a dirt bag and would probably do anything if it got him closer to the truth or was just horny. Him not doing Asuka is a bit unrealistic ok she is nuts and under age ,but, there is little in Kaji's character to explain the restraint on his part. Gendo Shinji is pretty vile though make Shinji a girl and it becomes as horribly possible as Rei Gendo. He is a grade one bastard and has a girl who would do anything for a bit of praise. Rei Asuka well Asuka is nuts so some sort of twisted love hate is possible. Full metal panic Souske Gauron. I wouldn't believe in a consensual relationship.