['V' - 'Uneasy Lies the Head']
As mentioned before, Erica is getting more ruthless in her war against the Visitors, particularly since they're responsible for her ex-husband and son being taken away from her. Naturally, since she'd be feeling lonely, she'd take to the nearest bad boy around, which would be Mr. Hobbes. Since their brief flirtation last week, they pretty much skipped all the courting and went right to the bumpy-bumpy (hey, that's war).
Given time, there would probably be some sort of relationship, possibly romantic, between Erica and Father Landry as well, since she obviously cares for him too. Perhaps that's a third or fourth season story line.