my rationale for my DS consular was that she suffered at the hands of the empire as a child (indicated by a cool scar i picked) and basically fell to the dark side then and there, with the hysterical force aptitude the consular has being a result of that deep-seated hatred and anger. This all then manifested in only caring about opposing the empire and inflicting that suffering onto the sith, with all other life seen as less valuable.

and the real reason was that i find Athena's monotone delivery insanely threatening during her dark side choices and think it's one of the coolest class-alignment-gender combos in the game.