Kingdom Hearts II Question about Kingdom Heart's Story Line.

Hello. I'm terribly sorry that if this post sounds noobish because I believe it sounds like one to me, but anyways... I'm just kinda lost on Kingdom Hearts atm, I love the storyline but I just messed up for a minute and I'm completely unorganized and I thought I should ask this question before I continued on with the game. Who is Roxas and what part does he play? And why does he suddenly disappear and then you start playing as Sora instantly and I just got lost here. Maybe it's because I didn't play the Chain of Memories, but I played the first Kingdom Hearts, and there was NO ROXAS!! : / Sorry to act like a noob but I'm just wanting to know. Thanks :)

 

Roxas is Sora's Nobody. He merged with Sora after fighting Axel for the second time.

There is only one minor reference to Roxas in Chain of Memories, you do not need to play Chain of Memories to find out anything about Roxas.

He was not in Kingdom Hearts because he was just born after Sora stabbed himself.

 

Well Roxas disapeared because...
SPOILORS
He fused with Sora because he is Sora's nobody that is also why he can use the keyblade. Roxas was in a virtual world when you play as him and it explains some scenes when the hooded guy calling himself ansem and the guy in red bandages (Trying to reduce amount of spoilers) are talking in a computer rooom.

 

Great thank you very much! :D