Sebastian is perhaps literally the universe’s smartest person. He is an incredibly brilliant mind, capable of planning out and predicting geological ages in precise detail. He is actually able to deduce from a stranger’s body language and facial expressions things that nobody else would ever expect to see – including the person’s name.
He often complains that he is the only being in the universe that truly has to worry about whether or not he possesses free will. If it is possible to envision every possible consequence to every potential action you might take, and it is always painfully obvious what the best option would be on social, economic and even ecological levels, do you truly have free will?
With that in mind, Sebastian prefers to limit his direct contact with people, for fear of adversely affecting humanity by corrupting their free will. He is actually hated by several people because of his ability to so accurately predict peoples’ actions and even speech. He is married to Melantha, and despite it being a horribly imbalanced relationship, she is stubborn enough to stick it out, and Sebastian does his best to stifle his urge to voice his predictions about her. They have a daughter Jessica, who is married to Empress Avra of the Rhanian Sphere.