You must exhaust all of his dialogue. First, go to Majula, head back to the way to Things Betwixt, and halfway up you'll notice a small hole in the mountain wall. Go in, past a small circular ruin, come out(no enemies in there), and he'll be straight ahead. Then, exhaust his dialogue until he repeats the same sentence upon talking. Then use a Fragrant Branch of Yore on Rosabeth in the building ahead. DO NOT PULL LEVER AFTER. Go back and talk to him, exhausting his speech again. Now he'll leave there upon next bonfire rest, and you can summon him for certain boss fights.Every time you encounter him now(just use wiki for locations) just exhaust his dialogue and he'll respawn at next place upon bonfire rest. Hope this helps a fellow Dark Souls 2 fan!