Hisoki is the epitome of the word ‘introverted.’ Growing up in a Skyrim orphanage will do that, but in his case, it’s also preferential. Trust nobody, need nobody. That’s why a native-born Nord won’t tell anyone the name he was born with- it no longer exists, and neither does he. ‘Hisoki’ is the only one here, and he’s pleased with that.
That’s not to say he’s a sociopath- he did try very hard, to say the right things at the right time, use the right inflections and so forth. He’s made a study of people: he just would rather not be near any.
Throughout his adult life, he honed his skills further, doing such work as could bring a profit while working alone. He’s picked up enough talent to use magical wards and heal himself in addition to his early acquired talent at calming people down so they’ll leave him alone. Make it so that, in their minds, he’s so harmless he may as well not exist, that’s always the goal. Easier to eliminate them, which Hisoki is quite practiced at, should that become necessary. Not that he’s evil- he’s not. He maintains a state of permanent equanimity with his current situation and does what is necessary. No more, no less, and no emotion. No doubt this explains his current predicament, bound and on the way to his own execution. Hisoki does find this ironic; he did kill the man, whom had it coming. Perhaps it’s time to balance the scales, he wonders...
He’ll join the college of Winterhold and study his areas of interest, but with no ambition. He will be happy to help out both the thieves guild and dark brotherhood, as both pay well for solitary work. He’ll side with the stormcloaks because they’re the underdogs, in his opinion, and he usually strives for a balance, in most things. He’ll side with the Dawnguard when approached. Live forever, being dependent on seeking out people? A double evil, in his opinion. Living forever is not how the game works, and most certainly not at that cost. Such dependence! He’d rather die, obviously. Everything else does, and one day so will Hisoki.