I think it was more of a spell or something cast on him to prevent him from saying anything and that if he did he would blow up. The “Mr. Face” guy must have been observing or something and just activated it cuz it seemed like the vampire dude didn’t want to die
The vampire dude literally said "i chose death"
I think it was more of a hypnotized response but I could be wrong
U could tell from his eyes that he wasn't conscious
What's the point of killing yourself to conceal the information you know when the person who asked literally invaded you mind i.e he already knows everything you did and you know