What happend to roxas in Kingdom Hearts 2?

Answer 1

The whole story is as follows:

After the events of Days, including the ending, Roxas is put into a simulated Twilight Town, where DiZ (Ansem The Wise) watches over everything and controls what happens. He is put in here until Sora is ready to join back with him and regain the strength Roxas holds. Roxas has no memories of his times in The Organization, probably due to Namine rewriting it so he would not escape.

He acts as a normal teenager, until all of the events in the beginning part of Kingdom Hearts II takes place, making Roxas confused and question what's really going on. Eventually, Namine explains that he is a nobody (Sora's, though that's not mentioned until later) and he was never meant to exist, and that his best friend is Axel, who had tried to reawaken his memories before to take him back into The Organization.

Eventually, he is called to the mansion in Twilight Town by DiZ, planning to join back with Sora, although Roxas doesn't know this. Axel tries once more to bring him back by using brute force, but fails, and Roxas gets most, if not all, his memories back, including those that belong to Sora. DiZ explains that Roxas is "nothing more than a tool" in awakening Sora to take down The Organization, and eventually, Roxas merges back with Sora.

Ultimately, Roxas lives on in Sora now.