Mostly that it was for the best. Scowl . . . needed to not be Scowl any more, needed to not be in charge or be a leader, and he just . . . wasn't managing that with Zexion and Fang right there. Things were breaking on an 'either you're with me or you're against me' line, and the one thing Zexion absolutely did not want to do was break Gokudera further.

For Nova to not be Scowl, there needed to not be a Hydra making him Scowl. As much as leaving had a chance of triggering plenty of 'you're all abandoning me' feelings, it was also the best way to say 'hey, we can look after ourselves, you aren't responsible for us'.

And Zexion, at least, has tried to stay accessible, if not geographically close. He has a passage down to Y and a portal out to E, and through those E was linked to Y as well, in addition to being just across the hall.

Tell me about something that surprised Gokudera in Thusia.