First time you meet him he threatens you with a dagger even if you have an alien warrior and a cleric in Shar armor standing next to you. The only reason he survives that encounter is basically Larian not offering a dialogue choice to kill him. He then sneaks up on you at night trying to suck your blood when your entire team is there in camp. He is a fool and I can see him being vulnerable to temptation.
To be fair, the meeting scene is obviously Larian's fault, and yeah the camp scene is weird.
