Here is what I think has happened to Roxas so far.
*Spoilers if you haven't played days*
When Sora released his heart, Roxas appeared in Twilight Town, where the Organization found him. In the Organization he became friends with Axel and Xion. After much confusion, Roxas leaves the organization, and battles Xion. Xion returning to Sora made Roxas go crazy-go-nuts and try to destroy Kingdom Hearts to get Xion back. In TWTNW he fought Riku, won, Riku became Ansem, and then Ansem won. Roxas was taken to DiZ, where he was implanted with false memories and eventually returned to Sora.
If I missed anything please tell me.
*Spoilers if you haven't played days*
When Sora released his heart, Roxas appeared in Twilight Town, where the Organization found him. In the Organization he became friends with Axel and Xion. After much confusion, Roxas leaves the organization, and battles Xion. Xion returning to Sora made Roxas go crazy-go-nuts and try to destroy Kingdom Hearts to get Xion back. In TWTNW he fought Riku, won, Riku became Ansem, and then Ansem won. Roxas was taken to DiZ, where he was implanted with false memories and eventually returned to Sora.
If I missed anything please tell me.