It's all in the mind!
Silas is insane. He is given to raging fits of madness at any time. He could be completely calm at one point, then be screaming and hurling things the next. An extremely dangerous character to be around; he won't hesitate to kill. He has convinced himself of the delusion that nothing can hurt him, and that pain is all in the mind, so a mere wound won't make him falter for long. The only way to truly stop his rampages is to destroy him.
He carries a dagger infused with basilisk venom, almost guaranteed to end the life of anyone struck by it within the hour.
He also has a small pistol shoved into either boot.
In his pocket there is always a fake cell phone set to detonate the instant someone opens it.
Silas was converted into vampiredom over three thousand years ago. He thought he could continue a normal life, until he was asked to change the woman he was deeply in love with. He did as she wished, but found he could not stop himself. He ended up killing her, and it was then he was pushed off the edge. He fell to insanity, murdering every vampire he could trace. A secret sect of the beings got together, and, with the help of a sorcerer, managed to lay a binding curse on him. He was imprisoned for three thousand years, until a foolish young vampire broke the seal, setting him free. He adapted to this civilization quickly, where he lay in hiding, waiting for his chance to strike.