Dexter and Jordan Chase are seen here on dueling treadmills. They each went to learn more about the other.
Dexter doesn't just deal with Rita's death on season five. He deals with a new character by the name of Lumen.

Dexter Season 5 Episode 9 Quotes

Lumen: Share something with her - what you did when you were her age.
Dexter: I killed the neighbor's dog.
Lumen: Well, don't tell her that.

Dexter (thinking to himself): Jordan is one tough nut to crack.
Jordan (out loud): You're one tough nut to crack; you know that, Dexter?
Dexter (still thinking): I wish he'd stop doing that.