Chris Messina

There's a good reason Damages' Chris Messina seems jittery most of the time he's on the screen — and it's only partly because his character is a soldier suffering from post-traumatic stress disorder.

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"I felt a huge responsibility to the soldiers to make it as honest as I could," Messina tells TVGuide.com. "I played a lot with sleep, and I think the most I didn't sleep was three days in a row. And I'm not a caffeine drinker, but I would play with drinking a bunch of Red Bull before the take. So, the sleep deprivation on top of the instant sugar-caffeine rush ended up making me very shaky."

Messina's Chris Sanchez has plenty of reasons to tremble. He's an employee for a Blackwater-esque private military company led by Howard Erickson (guest star John Goodman), and after Sanchez's last mission in Afghanistan went south, his entire unit was killed. Enter Sanchez's old high school friend Ellen Parsons (Rose Byrne), who wants to make Sanchez the star witness in her wrongful death lawsuit against Erickson.

As we saw in the previous episode, Erickson and his team will do anything to keep Sanchez quiet, including sending him back to the war zone that has so badly scarred him mentally and emotionally. Even so, Messina thinks his character may feel safer in combat.

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"I think he probably feels most at home there and [feels going] back maybe would help him find some peace in a way," says Messina, whose credits include Julie and Julia and Six Feet Under. "I think he wants to trust Erickson. He is trained to believe in his superiors and feel like they are taking care of him. He's trained to follow the rules, take the orders and not question them."

But in Wednesday's episode (10/9c, DirecTV), Sanchez's trust in the chain of command will be tested. He soon learns that the intelligence that necessitated his return to Afghanistan is phony. "This is the beginning of him taking the next step," Messina says. "He's going, 'What are they doing to me? Who can I trust?' There's so many people playing so many different levels of corruption. This is where he really gets a spark of, 'OK, I'm being lied to. Why?'"

This realization comes just as Ellen wins a court order to have Sanchez testify via video link from his barracks. But, at least for now, Erickson & Co. are one step ahead of Ellen and force Sanchez to falsify his testimony.

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"At this point he's not even ... aware that he's dicking [Ellen] over in a way," Messina says. "He wants to survive and his state of mind is so far gone, I think that what he's most thinking about is either surviving or dying. ... He certainly doesn't mean to hurt her. He wants to reach out to her — not only to help her, but to get help. It gets pretty dire."

Although Erickson seems to have silenced Sanchez, Messina suggests that surely won't always be the case. "Sanchez is like boiling water, like a volcano," he says. "There's so much going on inside of him. What is he going to do to get out of this pain? And how are they going to keep this guy shut up who is just getting more and more aware? That's the fun of this season: How do they stop Sanchez?"

Damages airs Wednesdays at 10/9c on DirecTV.