Well I didn't thought that it's possible before, I just belived that something like that is a firs step towards being Brony (thats how it was in my case, I enjoyed Brony music without even realising that), but...
Sometimes I'm playing basketball after work, and I do not conect with most of guys I play with not while the game, so most of them didn't knew that I'm Brony, but today I played in t-shirt with Twilight on it, and one guy suddenly after game asked me if I've read "Fallout: Equestria", I thougt that he's a Brony but he say he is not, that for a long time already he reads and enjoyes fanfics about MLP, but then he tried MLP itself he strongly disliked it. And yeah it pretty strange he said he loves Fallout and that why he read "Fallout: Equestria" and was surprised that it's about ponies, at that momen he didn't knew about MLP at all.
So, my question - do you know any non-Bronies who like Brony music/fanfics/animation but do not liked MLP itself or don't whant even to try it?