So, at the end of the cutscene at Yen Sid's tower near the start of KH2, Maleficent appears to return there, or that's at least implied. However, when you go there, Yen Sid is gone, which I thought meant that she either killed him or turned him into a heartless.

However, Yen Sid appears in the secret ending of Re:Coded, so this cannot be the case.

My question is, where did Master Yen Sid go during the events of Kingdom Hearts 2 until he appears again?

Thoughts?

After the party leaves, Diablo, Maleficent's Raven, arrives with Maleficent's robe that was left in Hollow Bastion. The three good fairies recognize it immediately, and their memories of its owner start to work magic on it and bring Maleficent back to life. She plotted to take over the Tower and announced her return with her trademark laugh.

It appears, though, that she failed, as she instead began targeting other castles all over for the same reason, and later, when the player can return to the Tower, there is no evidence that she ever held any sway over it. However, Yen Sid and the Good Fairies are completely absent, and the Tower is overrun by lesser Nobodies.

(Taken from Kingdom Hearts wiki)

It's just one of those things they don't really explain.

Maybe yen sid went to go fight off some heartless or maybe he went to another demension warning to creators of what's about to happen in kh2.

all possible but why then would he apper in KH:Coded's ending? I think that he was secretly talking with Micky and then went to watch over Sora untill Sora entered Kingdom hearts.

Lord Terra wrote:Maybe yen sid went to go fight off some heartless or maybe he went to another demension warning to creators of what's about to happen in kh2.

He probably tended to errands such as Xehanort's status or VAT's location

also possible...but from the images of the organization cloaks during the beginning of the story he already had there bodys all he needed were there hearts. and lets not forget that they found Aquas heart in her armor aswell as Vens heart in Sora at the end of coded like mikey said. so the only heart they needed was Terras but as Yen sid said Terras heart will be found when the other two hearts come together(Re:coded secret ending) but agian that also would mean that they would have to get rid of the back to power Xahenort.

They did not find Aqua's heart in the armor.

Mickey said he almost located Ven's heart. That is all he said.

Yen Sid said nothing on the matter about Terra.

Maybe he went to help the king, or when to the corridors of darkness to try and stop some other evil mess that sora couldn't possibly handle.