We're given the impression that they're relentless killing machines. As in, they don't rest, they don't lurk, they don't scurry, they don't have a homebase. (IIRC from the show, they were actually encroaching on civilization.) You can fanwank that in fact that *isn't* the case, that they have down-time where they hang out not killing or, I don't know, killing the ship they towed there (but why do that; plus, we hear screams and see revulsion from Serenity's crew. I don't know what they can see but it's not Reavers playing foosball). But that would not make them so much the relentless killing machines as the sometime killing machines who need a little non-aggressive downtime. (Still doesn't explain whatever the crew is seeing as they pass through.)

Now: explain why they can get through the Reaver belt w/o disguise, but they need it on the way back? Is it to pass through the Alliance disguised? Because it seems unlikely that the Alliance uses its visual to identify a ship.

We're given the impression that they're relentless killing machines.

I don't have that impression, actually. My impression is that they are mindless killing machines. Like zombies. They'll kill whatever they notice, but they aren't so bright or strategic. Which is why standing still was sufficient to allow them to drift through the first time -- Serenity looked like a non-working ship with no one on it. Reavers don't look that hard.

but why do that

Because they eat their prey live, and they scavenge ships.

explain why they can get through the Reaver belt w/o disguise, but they need it on the way back?

They're disguised both ways. Mal decides on Haven to go to Miranda, and disguises the ship there.

Now: explain why they can get through the Reaver belt w/o disguise, but they need it on the way back? Is it to pass through the Alliance disguised? Because it seems unlikely that the Alliance uses its visual to identify a ship.

Um, they didn't, did they? I'm pretty sure the ship was all gothed up for the inbound.

bon bon, I thought of that exact scene when Mal looks down below Mr. Universe's generator at the giant...spinny thing. Hee.

I wanted to take a tape recording of Sigourney Weaver yelling "Whoever wrote this episode should be shot!" and play it a second after Mal looked down at the generator.

I was sort of under the impression that the Reavers were like hyper-bikers; that is they are roaming and killing and whatnot, but then they go back to their "base" to kill and scream and party or whatever. Like Hell's Angels on super-crack, in space and as imagined by George Romero.

They're disguised both ways. Mal decides on Haven to go to Miranda, and disguises the ship there.

Oh, that's right. My mistake.

Because they eat their prey live, and they scavenge ship parts.

It's not unlikely, but why do it there rather than at the moment of capture? Everyone on the ship should put a bullet to their brain before then.

I don't have that impression, actually. My impression is that they are mindless killing machines. Like zombies. They'll kill whatever they notice, but they aren't so bright or strategic. Which is why standing still was sufficient to allow them to drift through the first time -- Serenity looked like a non-working ship with no one on it. Reavers don't look that hard.

I buy this, kinda, although these are the same Reavers that go after the Alliance ships at the Mr. Universe planet. But yeah, I guess I can see how their nature would lead to a sort of stasis, although it wouldn't explain the Reaver raiding parties as, say, the beginning sequence.

I'm taking this point well past its usefulness. Just that if the Reavers have the one goal of KILL THE HUMANS the Reaver belt seemed rather inefficient for the task, given what we've seen of their chasing capability. It is only helpful to create a sort of mindless obstacle course for Serenity, and of course as the cover for the dive into the Universe planet.

I think I must have gotten the impression somewhere that they were there to capture any boat that passed their way. Did Zoe not say that?

if the Reavers have the one goal of KILL THE HUMANS

Yeah, I never thought that -- like Jesse, I figured they ate/raped/killed what they saw, and sometimes sent out raiding parties when the entertainment didn't come to them. Exterminating humanity would have looked different, probably from as far back as the series.

If you buy they're not nomadic, bringing toys home for more fun doesn't violate anything I can think of.

I do think it's hard to underestimate Works For The Plot as an explanation for the actions of any fictional character, especially bad guys.