Sam Witwer came into The Clone Wars already carrying one big Star Wars voice behind him: Starkiller from The Force Unleashed. So when he was asked to play the Son of Mortis, the living embodiment of the dark side, he started worrying that the voice sounded too familiar.
That is when Dave Filoni gave him an explanation that sounded like pure Star Wars logic. But according to Witwer, he could tell Filoni was really coming up with it in the moment, just to help him regain confidence.
In other words, Filoni kind of “lied” to him, but in the best possible way.
Sam Witwer later explained that when he first came in to play the Son of Mortis, he did not have a strong take on the character yet. The Son was not just another villain. He was basically the dark side of the Force given a voice, which made the role huge and difficult to pin down.
“When I did the Son of Mortis for Dave [Filoni], I showed up with no ideas,” Witwer said. “I’m embarrassed to say that because you never do that. Thankfully, there wasn’t a lot of dialogue in that first episode, but I didn’t show up with a strong take on the character.”
As they worked through the episode, Witwer started to worry that the voice sounded too close to Starkiller, the character he had already played in The Force Unleashed. So he asked Filoni about it.
“I say, ‘Hey, Dave? Are we worried that the Son of Mortis kind of sounds like a generic version of Starkiller?’ Dave could see that I was losing confidence.”
That is when Filoni stepped in with the answer that changed everything.
“He says, ‘Well, Sam, you’ve got to remember,’ and I’m watching the wheels turn, and then he comes up with this. He says, ‘You’ve got to remember that Starkiller had a connection to the dark side of the Force. And the Son of Mortis is the dark side of the Force. So, it actually makes sense if they sound alike.’”
Witwer knew Filoni was partly making it up in the moment to keep him from losing confidence, but the explanation worked. If the Son was the dark side itself, then the voice did not have to avoid sounding like Starkiller. It could contain pieces of every major dark side presence.
“I went home with my head spinning,” Witwer recalled. “That’s how you play the character. I came back for the next episode and I started doing that.”
From there, Witwer began adding shades of Vader, the Emperor, and Maul into the Son’s voice. So Filoni’s little “lie” ended up giving him the key to the performance. It was not really about fooling him. It was about giving him just enough Star Wars logic to stop doubting himself and turn the Son into something much bigger.