Like solos in a jazz showcase or operatic star turns, the flashback stories on Lost serve as chances for cast members to get a little one-on-one time with the viewer. They flex a little character muscle, show some emotional range beyond survivor’s panic, and, with luck, deepen the trust between island inhabitant and audience. Some actors — like Terry O’Quinn — use their chances brilliantly, appearing to lift the series single-handedly away from the monotonous island isolation; others, unfortunately, only get exposed for the ensemble fillers they are.This season, Lost followers were most likely awaiting some debut back-story psychology from Season 2 newbie Ana-Lucia, played by Michelle Rodriguez. Ana-Lucia is the de facto leader of a group of wreckage victims from the tail of the plane — until recently not even known to the main cabin troupe — and a few weeks ago, it was her itchy trigger finger that bumped Shannon from the show. Last week, Ana-Lucia’s former life as a chip-on-her-shoulder cop, shooting victim and cold vigilante came into focus. How did Rodriguez do?Television may prove to be a more hospitable arena for Rodriguez than the movies, where her Girlfight cachet mainly led her down a path of stereotypical tough-chick roles. She’s not the most nuanced actress, but she has a mesmerizing hard-shell stillness to her beauty that allows emotions like sadness, fear and vulnerability to course across her face like wind over jagged rock. I was initially wary of Rodriguez’s contributions to this fascinatingly uneven hit — she’d been all confrontation and steeliness till now — but her solo turn had heft. Welcome to the jungle, Michelle.