Remember that Roxas fighting Sora only happens inside Sora's head, so i would actually guess that Roxas remembers Xion after joining Sora again just as Xion did. I'm not a Riku X Xion supporter, but one of the reasons for that might be that i don't care about Riku in the first place, i only see him as a powerful companion in KH2, that is pretty much it, and because of that, i fail to see any romance between Xion and Riku at all.
I still don't he does but oh well , I just don't see it after playing Kh 358/2 days after the battle with Riku. But then again there is re:coded. Data-Namine reveals to data-Sora and mickey that Xion is one of the people while gone, she still is connected to Sora's heart. As you can see I don't Support Xion and Roxas as a couple. I just see her as a good friend to Roxas and Axel. I seen a couple of caring moments between Riku and Xion.
But its a cool picture and a cool idea, i really like it, and i do like Namixas a lot.
So i approve :3
I'm not a Riku X Xion supporter, but one of the reasons for that might be that i don't care about Riku in the first place, i only see him as a powerful companion in KH2, that is pretty much it, and because of that, i fail to see any romance between Xion and Riku at all.