I know Tsuchimikado was always a backstabbing son of a gun. From what we've seen in the novels he's added to Touma's misery a bunch of times humorously and not, but if he really does gouge out Seria's eye whom we assume is a reasonable person (even if it gets perfectly healed by the end) does anyone find that crossing the line of "we will still be buddy-buddy in the immediate future?" He's apparently all angry at his sister being in danger, even though he's a double-crossing spy... Perhaps the novel will flesh out his motives in a better light, but as of now they just make him seem like a douche at this point IMO.
To follow up on that point, if Aogami ever does become an active character I find it more reasonable to expect he'd help Touma alone (no delta squad) if Kamachi's tease of Index and Touma, Aogami, Komoe-sensei back stories are to be believed. Assuming Those latter three would be grouped together it makes it seem Tsuchimikado is the odd man out [later addition] to what would become delta squad and Touma and Aogami knew each other longer, assuming I'm remembering that tease correctly
End rant.