Star Trek: Voyager - Ranking Every Major Character Worst To Best

Martha Hackett provided the role of Seska in the first three seasons of the show, who started out as a Bajoran Maquis, then was revealed to be an infiltrator of Cardassian heritage (because those dastardly Cardassians get everywhere).

Presumably to fulfil some base desire to just be pure evil (or because the Doctor would have eventually discovered her DNA), Seska defects to join the Kazon Nistrim and tries to smuggle them Starfleet technology. Seska's villainous role had a limited shelf-life, however, as how do you maintain a recurring antagonist when the principal ship is meant to be always on the move. As in, moving away from the enemies it's made along the way?