Thelis doesn't leave... He is always online, the forum just hides him at night.
Thelis doesn't need to eat or sleep either. I mean come on.. He's Thelis..
Everyone calls everyone else a "kid" because they automatically assume they are older or think that they know better than who they are calling a kid. It's actually more of a MMO thing. Higher leveled players or those with lots of currency call lower leveled or poor-er players "kid". ehh. Such is life