Wait what? She's tsundere? Zessica is not tsundere. She's a genki Flirt. Mikono, on the other hand,
is (although a mild example). I really enjoy how she deals with jealousy. It's refreshing to have it internalized and attempted to play it cool. She's pretty caring and protective with her friends.
Blaming Mikono?
What?
If anything she's annoyed that Mikono seems stringing Amata around without giving him a clear message (hence: "If you don't want him, I take him") which is... well, true (but you can blame it on her mild tsundereness and past life)! She doesn't blame Mikono, if anything she developed an inferiority complex (similar to what Mikono had with her).
The best thing for Zessica is to take interest in a girl, anyway. No way that het shipping will end up happily in Aquarion. LOL.