Skelos is a seeker of cosmic secrets that would be better left hidden.
Origin: Outcast and banished by fellow yuan-ti due to religion dispute, perhaps even teleported to a cold area as a punishment.
His spellbook's cover is iron. Engraved on the front is a Memento Memori, a reminder of death, in his home language. (He is a necromancer, Afterall).
It translates to "We only dance for a short while, and then time demands its toll".
Outside of his search for secrets, he also wishes to construct a monument to his memory.
Skelos is considered a heathen by other Yuan-Ti due to keeping Yuan-Ti gods that were forgotten in favor of new ones.
During down time, he will write. Like, a lot, Philosophy, observations, drawings of local fauna, diary, poetry, melodies, cataloging unknown creatures he meets.... (Probably after said creature is a corpse)
Despite being a necromancer and leaning to evil sounding spells, he does have an interest in abjuration. He is not a "one track wizard".
Personality: Hates yuan-ti cultists who disagree with him, believes that he can do many thing
Ideals: He would like to prolong his life for as long as possible, up to and including centuries if he could, but his brain is pragmatic and thus he would like to build a monument of sorts as quickly as possible, which would long out last him. (He knows he will die) The cosmic secrets he wants do include life expanding things.
Bond: He likes things that are engraved in solid rock or metal. He would like to inscribe secrets that he learns like that, perhaps on a big pillar.
Flaws: Over confidence tripping him up if he gets far ahead, being arrogant/dismissive of others due to being a cold-blooded yuan-ti as well as a sage, and being rather nihilistic and callous to life. Talking to skelos is like talking to an aberration at times.
Sidenote: If yuan-ti are not allowed I can change the race. I see that yuan-ti were not a thing to select. I would prefer a snake though, since my character is a reference to an obscure mentioned character in Robert E Howards stories, and that character is a reference in and of itself to the-seikilos-epitaph.