The short of it is that he's a former slave who has spent the vast majority of his life serving various masters in a foreign pack. His spirit was broken pretty early on; obedience is the path of least resistance and he's stayed out of trouble over the years by being a model servant with a flattering silver tongue. At this point he's come to depend on the routine and authority that comes from receiving orders. He wouldn't know what to do with himself otherwise.
Hemlock is observant, well-spoken, and enjoys the company of others. Under different circumstances he might have been very charismatic- as it is he's also cowardly, shallow, and quite willing to throw his companions to the wolves, as it were, to ensure his own wellbeing. He makes a wonderful listener but not necessarily a good friend. He's pretty maladjusted and his sense of compassion and loyalty is stunted, to say the least.
Now middle-aged and past his prime, Hemlock finds himself pawned off as a diplomatic 'gift' to the nobles of Highvalley. Falling back on the only thing he knows- servitude- he's determined to make himself indispensable to the royal family and secure his place in the pack; there is nothing he fears more than rejection and the prospect of having to fend for himself.