Dexter has a lot to teach Lumen on season five. He doesn't really want a co-conspirator, but he's stuck with one.
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Dexter is forced to take on a protege on season five. This is a shot of him and Lumen from the episode "First Blood."
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Dexter Season 5 Episode 5 Quotes

Dexter: Harry's right. I have to convince Lumen to do what I never could: to move on.

I want to believe that smile, that watching your mother die hasn't changed you the way that watching mine changed me.

Dexter [on Harrison]