This one is actually meant to be set within the show, instead of in fanfiction land. Everyone knows about the dreaded Hawaiian shirt that Revy bought Rock, which he never wears despite her complaints. In the first episode of the Japan arc in season 2, it shows Rock in his room and the shirt is hanging on the wall. I thought, "Why would he keep it there?"
The Shirt-Rock always thinks of it as "The Shirt", capital letters and all-is never going to be worn. Rock doesn't know what Revy was thinking with it; it's so awful, wearing it should be some kind of punishment. But he can't throw it away, because you don't throw away a gift from someone. It wouldn't be nice to Revy, to throw away The Shirt. Not that "nice" is really in her vocabulary, but still. It was a gift, and you don't throw away a gift, regardless of who it's from. Rock certainly isn't keeping it just because it was from her. That's a ridiculous idea. And the reason he keeps it hanging on the wall like some kind of artwork, even though it is a far cry from that, is because he doesn't want to get it mixed in with his other clothes and accidentally put it on one morning. It certainly isn't because looking at it makes him think of Revy. That's just as ridiculous as thinking he only keeps The Shirt because it was Revy who gave it to him. That's not how it is. There's nothing special about that shirt at all.
fin
I really wasn't sure what this should be called, because it isn't exactly romance though the implication is there (sort of). I went with friendship because it was meant to be set within the canon.