I'll start this off by saying I have played 358/2 Days! Extensively. I even kept a gaming blog on it on my journal, and I helped both my girlfriend and Roxas's mun to finish the game. I know this game by heart already.
This said! THIS POST WILL PROBABLY HAVE SPOILERS.
I went into this game expecting to love Xion. And I did! I love her lots, and I love her relationship with Axel and Roxas. I WELCOME ANY AND ALL XION WHO WISHES TO PLAY IN GARGLE. However, since Xion being dead erases all memories of her existence to anyone who, apparently, isn't Roxas (and even then Roxas is grasping at straws a lot), until we get one, Axel does not remember her. So I'm not ignoring her because I DON'T LIKE HER BAW, but rather because it's all I can ICly do.
So, while OOC-ly I actively welcome a Xion, ICly Axel doesn't remember her right now, and when one does come in, it won't be all happy sparkles at first-- memories are EXTREMELY important to Axel, and knowing his were fucked will make him mad, plus, how Axel and Xion last saw each other wasn't exactly ... good times. But Axel genuinely likes Xion, and playing him any way else is OOC, so that won't last. :)
Basically: I LOVE YOU XION BUT ICLY YOU DON'T EXIST RIGHT NOW, SORRY