@AbsolisWhy would the God Emperor suddenly side with some nutjob attacking someone he could likely tell is on the alien's side? Why would he 'shoot the messenger', since that's essentially what the Ethereal is, because some psycho bitch is in a bad mood? Unless you thought I mean Nova would side with Ethereal, which would also be silly.
By Ruiko's sass I meant she'd kick the Ethereal's ass along with Cyano out of sass. You know, because it kind of acted like a pompous asswipe when 'evaluating' her potential? But then again, she also seems to be a bit scared of its powers. That and it knows where Misaka is. I don't think she'll side with it though, because of what I just stated.
The 2 vs 1 thing is Biollante evidently siding with the Ethereal due to her current loyalty.
Apocalypse seems busy but everything is possible with that asshole.
Edit: Yeah, some. Nothing of consequence. I don't think they'd give her something where she could plant a worm or something.