See now this is the thing I find interesting. I don't think Cinder has told Neo how deep this all actually goes. I don't think Neo knows that Salem even exists. There is only one hint towards her knowing and it's way back in like Volume 2 or 3 and it's Roman who makes a statement that makes it seem he's in the know. It'd be interesting if Neo found out (if she hasn't yet) just how BAD things are and either bows out or does the heroes a solid before leaving. After all, she was just a crook. That doesn't mean she'd be in on bringing the world to ruin. In regards to Emerald and Mercury, those two are so clearly over their heads, it's almost writing on the wall that they really want out of all this.
In regards to them being power hungry, that's purely on Cinder. She's the one always harping on and on about it, while Emerald sticks with her because she believes Cinder actually cares about her (debatable) as well as feeling she owes her for getting her out of the terrible life she had before hand. From what I remember of Mercury, it's because his dad was an assassin (I think) and so he feels he has no choice but to be that.
In regards to them being power hungry, that's purely on Cinder. She's the one always harping on and on about it, while Emerald sticks with her because she believes Cinder actually cares about her (debatable) as well as feeling she owes her for getting her out of the terrible life she had before hand. From what I remember of Mercury, it's because his dad was an assassin (I think) and so he feels he has no choice but to be that.