Tessalar was a vain man, with a liking for elaborate dress. He was unwilling to trust anyone, to the point of paranoia. Tessalar had ambitions to form his own noble house.
When he wasn't attending parties, Tessalar stayed mostly in his magically fortified house.
Tessalar was once a mercenary mage, tutoring and casting spells in exchange for treasure, which he spend to finance his magic research.
One day, he came back from an expedition into Undermountain with so much treasure that he was richer than any man of his age. The truth was that he stole the hoard of the sleeping black dragon Vulharindauloth.
Soon Tessalar established himself as a fixture of the parties in the Sea Ward of Waterdeep, often casting illusions and pyrotechnics for a sponsoring noble. As deduced by many, Tessalar wanted to use his noble connections in order to found his own noble house, but some family patriarchs knew the truth of his ambitions and easily used him to their own ends.
Tessalar became increasingly paranoid about Vulharindauloth, who established himself near Skullport with the objective of discovering the thief of his hoard. Tessalar hired dragonslayers at great expense to find and kill the wyrm, though without success.