BTW, I absolutely adore Billy Coen. ^_- Aside from the fact that he's quite yummy (arm tattoos and all), he's a man with secrets. And we all know how I like guys with deep, dark, secrets.
In RE0, Billy's gruff and cynical, but he's quite obviously also a loyal, honorable sort of guy. Certainly, it seems pretty damn unlikely from his behavior and actions in RE0 that Billy had anything to do with the massacre of 23 of his fellow soldiers (so sayeth the court martial document in the official strategy guide) and a whole village of innocent people (from the game flashback). What seems fairly clear is that he was framed by somebody, most probably by his rat-bastard superior(s), with or without Umbrella's involvement.
However, it's also fairly obvious that Billy knows... things... that your normal run-of-the-mill soldier would not. For one thing, he seems to take this whole viral outbreak mutant zombie-fest amazingly in stride. Granted, that's a characteristic of practically every RE hero(ine), because if you waste time and energy panicking, you die. ::snerk:: But still I makes me wonder if he's encountered something similar to this before. Hmmmm.....
Another curious note -- where the hell did his comment about 'Marcus was still experimenting with the Mother virus' (paraphrased) come from? Where would a 'normal' soldier pick up this little tidbit about Umbrella's viral research? I suppose that it could simply be a goof on the game's scriptwriters and they meant to refer to the Progenitor virus, in which case it's quite possible that Billy just happen to run across a file in the mansion that told him about the Progenitor virus. But still, it's... interesting.
And then there's Billy's flat refusal to elaborate more on the massacre and the events afterward. It is quite possible that after the debacle of his last military mission, he somehow got involved with Umbrella or possibly even someone else conducing similar research. Say like... the government? ::pondering conspiracy theories::
Ah, lots of nutritious plot bunny fodder there! ::points:: See, there's one right over there involving how Billy got those fascinating tribal-style arm tattoos!
As for Rebecca, I'll definitely go for the much calm and competent RE0 version, rather than the wimpy REmake (Resident Evil remake for GameCube) version. I'll just pretend that that while she was out of sight in REmake, she was doing her own share of exploring and kick-ass. And when we do see her in the REmake, she's just happens to be physically and emotionally worn down. Hey, it's my prerogative as a fanfic author! ^_-