Viduus

Daytime school teacher, nighttime ancient being/soul-shearer in an ongoing existential crisis. 

Appears quite modestly during the day, and around the small town he's decided to 'settle' in for now, but appears more as pictured when he teleports around looking to socialize. Always looking to form a deep friendship or romantic bond. If these fizzle out, then so be it - but if the relationship ends in such a way that Viduus feels slighted or cheated, he sheers the soul from his previous-friend and goes home to sulk about the frailty of emotional connections.

Personality - smart, can be charming, intelligent, deep listener - interested in people's motivations and emotions. Jaded and sometimes sarcastic; not appreciative of naivety unless coming from children. 

Obviously would prefer to be with someone, or just to have a steady friend, but after so long - he knows how rare these things are, having only found a handful of satisfyingly 'good' relationships in his millennia of existence.

While not particularly physically strong, he is also not killable by normal creatures. Not meant to be a balanced-power character.