Yes, running from humans. As he says at the end of series 3 to Herrick something along the lines of deserting them when they let you do and doing what he needs to survive.
Ah, he is angry at humans, and yes he's running back to what feels like a safer place. Its a combination of things driving him back, his anger being the explanation he uses for himself. But he was disillusioned with the vampire before and he will be again even without the whole take over the world plan.
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In this little enclave of the lost I witnessed the very best of being human.