Capítulo 642: I agree not to lie and answer honestly

"Vincent. Can we expect the bringer of death and destruction to be a good person? Can we expect such a person to be on our side?" Asked Lucas with a profound expression. 

[Lucas is straightforwardly saying this. He is trying to question if you will be an asset for the Lusterfall Kingdon or not.

As Kazumi put it, both sides were currently in a delicate situation. Vincent needed to be accepted by the people in front of him for his survival, while Anna and Lucas couldn't merely accept Vincent as he could spell the doom of Lusterfall Kingdom.

In the impending war against the Selos Kingdom, using poison to fight poison could leave the user poisoned in the end. A coin has pros and cons. It has a frontside and a backside. It has the good and the bad. Accepting Vincent could be beneficial or disastrous.