[DingoEnderZOE2]

[QUOTE=rexlunae]

Spoiler for all question arcs:

Shion had become aware of that Mion recently had developed feelings for Keiichi, because Mion had needed her help to cover for the lie she told Keiichi at Angel Mort (I think that was really Mion the first time).

You got some questions in there that needs to be cleared up before that theory can be valid.....Who was the person who didn't know what the heck Keichi was talking about when he returned the lunch box to her? And why would she be confused about it if she was already aware of the plan ahead of time? As for Keichi's meeting with "Shion" at the Angel Mort maybe Shion was embarrassed about the outfit from the eyes of someone she's well aware of but not yet fully acquainted with. Plus in the look she gave Keichi out the window after he left just seemed to telling us the viewers that shes thinking "Hmmmm so that's Maebara Keichi.....my prey." As for the lunch scene, If that really was Shion why did she seem so flustered when she was handing over the lunch when we can obviously tell she's not the shy type at all(Apparently after she's well acquainted with a person.)

Your other theories sound nice though.