By a process not yet fully understood, some Tiste became Soletaken by drinking T'iam's blood. The female Soletaken thus created subsequently referred to themselves as T'iam's daughters. It seems that the transformation also required T'iam to mate with a male Tiste.
Osserc referred to the Soletaken as an extended family whose most precious (or if not precious then certainly most popular) trait was treachery and betrayal.
The creation of the Soletaken resulted in T'iam's death.