Well, this episode certainly had some interesting moments. Did Mara turn Duke into an ether factory?
I'm guessing no. He'd be way too powerful that way, and unless they introduce some silly rock/paper/scissors (kryptonite) which would be lame ... I'm guessing there are some major limitations. The writing here has typically been a fair bit better than Heroes.
Based on what happened I'd guess when he kills someone, he absorbs the aether that was used to create that person's trouble and then passes it on to the next person he touches ... unchanged (it was the same oxygen trouble).
The interesting question is whether he has any control over it. And with that in mind, whether he has access to the previous troubles he's 'removed'. Since we've never seen him absorb aether before, that would be kind of weak ... but I suppose they could write it off as having been contained in the blood he absorbed.
If I had to guess though, I bet it's only from this point on?
Charlotte is Audrey's mother? How does that even work lol?
She's Mara's mother. Not sure what you mean about how does that work? Do you mean because of her age?
We really have little information on who they are, what they are, or where they come from. It could simply be that time moves differently on the other side. Since Mara (in whatever form she happens to take) only comes over for a limited time and then goes back in for a generation ... she doesn't really age. Then again, for all we know Mara and the others don't even age (or age slowly) even while here. I imagine this will get explained in due time.
One possible scenario is that they do age while here (but don't on their side) and Mara actually was originally young when she first started coming over. That could explain their ages seeming similar. Only problem with that is so far they seem to have implied a start date (Croatoan?) ... and all examples of Mara have been around the same age. Then again, that might be a red herring and it's been going on far longer?
Main problem with that theory is that would mean Mara was that fucked up as a young girl ... and was 'cursed' or whatever to try and stop her as a child. I guess that isn't so much a problem, just that it's pretty fucked up lol
Anyway, I'm gonna assume Charlotte was either released when the barn imploded or came through a thinny.