I think he disappears and you don't see him anymore
You don't.
Continue your journey :]
Yo mammas house
He pops up out of no where and tells you news about N then leaves.
you go to nuvema town to your house and talk to looker
Looker goes away after you find the Seven Sages.
looker only comes when you beat the game and he gives you a Super Rod and you meet him when you find the seven sages.
After you have Looker arrest the last sage out of the Seven Sages, He should thank you and he should also tell about a boy who sounds exactly like N, who has been seen with a dragon pokemon somewhere far away... ^_^
watch Youtube videos that's how i got them
Looker went asking the seven sages about their plan and after that he went back to sinoh to do some resreach. He will come back after you get all the 3 legendry pokemon Virzion, terrakion, and cobloin. he will blab something about your legendry pokemon and after that i dont know.
looker? you must have the question wrong, there is no one named looker in either B&W of pokemon (why because i named my character looker! :D)
Looker says good work and there's been a sighting of an N-ish person in a nearby city that he's gonna check out