WARNING: This article contains spoilers for Helstrom, now streaming on Hulu.
Hulu's Helstrom gave Daimon's iconic chest marking an origin of its very own. In "Underneath," the eighth episode of Season 1, he revealed to Gabriella Rosetti that his father had carved it into his chest with a demon-killing knife.
The episode picks up just after Daimon survived an attack by the Blood. After discovering the knife in Caretaker's arsenal, the Blood attempted to kill Daimon by arranging a meeting that turned into an ambush. He was able to throw off his attackers, but he was shot in the process.
When he returned home with Gabriella in tow, she demanded that he take off his shirt so she could examine the wound. He did so, albeit begrudgingly, and revealed it was already beginning to heal. Due to her proximity, he sensed the knife in her pocket and asked about it. When she produced it, he revealed his father had used it to mutilate him.
"That's what did this," Daimon said, referring to the scars on his chest.
"It was your father's," Gabriella realized as she passed it to him.
Staring at it, he explained, "It's the only thing I've never healed from, the only thing that ever left a scar."
"Could the Blood have killed you with that?" she asked.
He didn't answer. "The energy coming off it is so old, violent," he breathed. "Feels like him."
Due to the knife's mystical nature, Daimon's scar also appears to have mystical qualities. For instance, he attempted to tattoo over it in one episode, only to mention that the ink always fades away quickly. Additionally, it begins to glow and burns through his shirt whenever he uses the full extent of his magical powers. The meaning of the marking itself remains unclear.
In the comics, Daimon's chest marking isn't a scar so much as a birthmark. Since he is the son of Satan (or, later, a demon), he was born with a Darksoul, the demonic equivalent of a human soul. His Darksoul manifested physically as a birthmark in the shape of a pentagram, which went on to become one of his defining features.
Marvel's Helstrom stars Tom Austen as Daimon Helstrom, Sydney Lemmon as Ana Helstrom, Elizabeth Marvel as Victoria Helstrom, Ariana Guerra as Gabriella Rossetti, Robert Wisdom as Caretaker, June Carryl as Louise Hastings and Alain Uy as Chris Yen. The series is now available in its entirety on Hulu.