Another thought just occured to me... We don't know anything about the timing of Avon or Vila's arrest. It's doubtful that there's a ship heading out for Cygnus Alpha once a week (I'd suspect once a year might be more like it), so either or both of them could have already been locked up for a long time before we even meet them. Sure, they were in different holding cells while awaiting transportation on the _London_, but presumably they were held somewhere else before that. Maybe they were locked up together? Or, even if Vila had been caught quite recently, if he was held in the same facility as Avon he might well know about him by reputation. I would think that Avon would likely be the sort of prisoner who gets gossiped about. :)
(I've seen a lot of fanfic postulating that they knew each other before their respective arrests, but I don't buy it, personally. Not only would it be an awfully big coincidence (yeah, I know, not that that's unusual for B7), but I just don't get that feeling based on the way they interact. Plus, Vila pronounces Avon's first name differently from the one person that Avon actually acknowledges as an old friend, Tynus.)
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