Venatrix was originally born a Blood Elf huntress. It was different the second time, though. Venatrix sets on a journey to hunt down the two men who ended her first happy life. Stories like these always have an alternative. The main character would somehow see the light and realize vengeance is a waste of your second chance. But life's unfair, and Venatrix wants the two men who ruined her to taste their own medicine. Besides, what else could she do besides look for vengeance?
She is, after all, now a death knight.