§·§·§
He convinces himself that it's not really a prison, that he's not really limited to this tiny strip of land; there's mainland just half an hour away and, should he want it, there's an easy way out of the mainland and the world. Mickey made sure he knew there would always be an easy way out; he's thankful to the King for that. He is thankful for many things the King gave him and helped him get.
He convinces himself that there is peace in this sort of life, with the sealing of the worlds and the return to their home. His parents were so glad to see him, they had thought him dead or lost forever; he's grateful for their love, but it's also the first time he truly felt it. He is grateful for their promises of care and love and a future.
He convinces himself that his friends are truly safe, that nothing more will disrupt their lives and their homes. He will never forget how Kairi stuck by him, how she made Sora believe; he'll never forget that moment of reunion, of unity and friendship. He knows that what they have now is stronger than it ever was and it will not be broken, not for anything. It is a very pleasant feeling, not being alone, having them to rely on.
So, he closes his eyes and convinces himself that he is happy to be back, that he is happy to be sitting on this trunk again; that he is happy that everything is over and they are all whole again, ready to start anew.
Of course, the flicker of pleasure and excitement he feels when he sees the bottle with the message inside, tells him that he hasn't done a good job of convincing himself.
§·§·§