It squicks me too. I went off on this when Sally was here in April and she laughed and laughed at how upset I was about people slashing John. I even saw a fic somewhere that had John/his daughter and I had to turn off the computer and step away, because NO NO A THOUSAND MILLION FUCKING TIMES NO.

Now, I've got no trouble believing John can't get it up without medical help or an extra long hand/blow job. But he doesn't fuck men, his daughter (or his son, there is a son isn't there?), and he really still loves Holly and will until he's dead and buried.