I've read on here that Cloud seemed upset in FFVII - Advent Children, and i've seen it all over the net. I suggest you watch the gorgeous opening scenes again. The reason is explained by the girl who is talking over the intro. She says 'sadness was the price to pay'. When the lifestream used itself as a weapon, 'sadness was the price to pay'. That is why Cloud is sad. That is why most people are sad in the film.

This is just something i thought bout and posted. Anyone else got things like this to share?

I'm gonna start FFVII again, in the mood to play it now!

Well...like in any story of this type....Cloud is a typical self tormented hero stereptype...in that respect he has to torcher/torment himself during the entire film, (or game) in order to win in the end. Or he will be torchered and tormented by other factors (Sephiroth, memories etc.) or even he will not be himself ( in game he is split in two..this is very common). And all this to defeat his own personal demons and to restore the order to the world.

Feeling of sadness or him being sad, feeling helpless, being silent, withrawn from the world and the people around him, madness and being lost, feeling sorry for himself, self-loading and especially feeling guilty over some tragic event from the past that he failed to do or failed to succed in (for example. :save friends in this case..or lover... latter usually the case in this kind of tales) is a another sterotypical set up for this type of character.

hes sad cuz he thinks he cant help anyone, and he let aerith and zack down.

He's sad because he thinks its a 'sexy look'. I really wish Tifa would have given him a good slap.

Actually, Cloud had cheered up significantly earlier by the time her returned from the Forgotten City. His encounters with people from the past and present seemed pretty vital to his "recovery" from his post traumatic stress he seemed to be suffering. He has his vision of Aeris telling him to snap out of it, he's recalling the harsh words of Tifa to snap out of it and even Marlene and Vincent chime in. Plus he has the immediate issue to face; his failure in the past has been making him scared to be proactive in the present, fearing he will fail those he lovs (Tifa, his family, his friends), and now he's in a dilemma where lack of action could indeed risk his family and friends. So ALL these elements come into play in giving Cloud a lighter load of pain and a more proactive stance. Personally, I think Aeris' has done her part of the healing in the Forgotten City, the bit at the end is Aeris saying farewell as she knows Cloud can move on with his life now without being trapped in the past over the pain of herself and Zack (who appears equally in the end farewell scene).

And yes, he was upset about Zack as well as Aeris. I'd suggest Aeris had slightly more relevance because a) the experience of Aeris' death would be far more real; he was conscious and just light a nightmare, unable to move to stop the terrible events happening in front of him.
b) He had said he'd be her bodyguard and just like everything else in his life, he blew that promise.
c) The audience have stronger memories and ties to Aeris than Zack.

Though I think the Compilation will show us Zack's death was VERY important to Cloud through Crisis Core, and AC does have him start hanging over Zack's grave, so while I think Aeris' death hits him from several angles, CC will show us not to underestimate his relationship with Zack.