List of Dexter characters
On a visit to his sister, Dexter and Debra both feel as if they have been drugged; just before he passes out, Dexter sees Hannah standing over him. When he later regains consciousness, Dexter begins investigating Hannah, and finds that she has changed her name and married Miles Foster (Julian Sands), a wealthy businessman. Dexter goes to see Hannah, who says that she had wanted him to kill Foster, but changed her mind after realizing she is still in love with Dexter. Foster warns him to stay away from Hannah, and has him beaten up. Dexter goes to Foster's boat to protect Hannah, but finds that she has already killed him. The two of them dispose of the body, and promise to watch out for each other. The two end up having sex and rekindle their relationship.
Dexter (season 5)
Meanwhile, the subplots throughout the season focus on the relationships of LaGuerta and Angel, who have made their marriage public but are having marital issues, and of Quinn and Debra who become romantically involved. When Angel gets involved in a bar fight which gets him in trouble with the Internal Affairs Department (IAD), LaGuerta saves him by helping IAD set up a sting on another cop who is under suspicion, Stan Liddy. Liddy develops a friendship with Quinn, their common bond being they were both "betrayed" by LaGuerta, and Quinn pays Liddy to investigate Dexter. Debra remains unaware that Quinn suspects her brother is Kyle Butler.