The Character Luke was very undeveloped (Spoilers)
The character Luke was very under developed, in fact he was so under developed that it just took me out of the story.
If you look at the other four, you had:
1. Vincent-Who was a sex addict that wanted to sleep with any women regardless of who she was related to.
2. Chris-Who was stuck in a bad relationship with his wife, who fell for a prositute whom he had more than connection with than his wife.
3. Marty-Who was a loud mouth party boy, whose wife left him when she found out he was cheating.
4. Phil-The half Brother of Chris who is a drug addict, women abuser, marrying into a wealthy family to only screw it up.
5.Then there is Luke- Who was just boring and stuck in a boring relationship,
I also felt Luke was not as developed as the others for the following reasons:
1. Luke sort of had a thing for Sarah even though it was never indicated on screen, after the San Diego night, the audience never saw him have communication with her or sleep with her.
2. The audience never got a reason why he was video tapping the others or what his intentions were.
3. Why would the others would side with Luke instead of Vincent when they found out that he was taping them. They also never questioned him on what he was going to do with the rest of recordings that he did not turn into the police. They basically just roughed him up and then went along with his plan.
4. Why didn't the police press Luke on why he was taping Vincent and what he was going to do with the recordings that he gave to the police.
5. Lastly, why were the other three not arrested as accomplices in the blackmail of Vincent and the murder of Sarah?
The whole Luke story line felt under developed and forced as a way to come to some sort of closure to the film. I think if Luke was reworked it would have be a different film and more intense, basically it felt like Luke was plugged in to move the plot along.