When Theron told Silas to stand outside of the room, Damon was also standing outside with Silas, and the room's doors were open.
Theron was standing in front of Velric, a little further away from the bed. And while looking at Velric, he turned his head toward the left side and took steps there.
Seeing all this, Silas was not understanding what Theron was exactly gonna do.
But then Theron stretched his hand and grabbed the knife and came back to stand in the same position, but this time close to the bed.
And suddenly, without any second thought, he slashed his palm with that knife.
"Theron, why are you cutting your hand?"
Silas panicked seeing Theron doing this and was about to step inside, but Damon held his hand.
"Silas, let him do whatever he wants. Just stand here quietly."
Hearing Damon, Silas calmed himself, but his heart was still beating like crazy.
He even started sweating, 'cuz he was scared if something happened to Velric and Theron.