!

[Luara]

http://www.kingdomhearts.be/trailer.php?image=kh2intro_0106
who's this guy??...
http://www.kingdomhearts.be/trailer.php?image=kh2intro_0090

[* White Aeris *]

He is Marluxia according to http://en.wikipedia.org/wiki/Kingdom_Hearts_2. He is part of the Organization XIII.

[Skyblade]

Yes, that is Marluxia, the Organization XIII member who was given custody of Namine and Castle Oblivion. If you watch the entire video, you will be able to identify him by his scythe. He turned against the Organization in Chain of Memories, using Namine to manipulate Sora's memories with hopes of turning Sora into his puppet. Marluxia would then use Sora's power to take control of Organization XIII. However, due to the actions of Axel, a double agent who pretended to side with Marluxia but was actually still loyal to the Organization, Namine was set free and helped turn Sora against Marluxia, who was destroyed at the end of Sora's story in Chain of Memories.