Chief Matthews assigns Debra Morgan as the new Lieutenant to LaGuertas dislike, because she promised the position to Batista. She makes it clear that she will depose Debra if she does not do as shes told.
Does Deb become a cop again?
In mid-season, Debra and Lundy develop a romantic relationship. While living in Dexters apartment, Debra keeps leaving the place a mess to the point where Dexter says, half-jokingly, I will not kill my sister. At the end of the season, Debra has regained her confidence and her police work is back to scratch.