Dallas was almost certain Barrett and Edward had consumed a toxic substance called vervain.
Vervain was a toxic substance to the vampires and it annulled their powers.
That is, Barrett and Edwards couldn't have gotten affected by the memory erase he had infused on them and had known exactly when he did it.
They both carried a weapon that could be used against him.
However, that wasn't his burden at the moment, though. He had Lydia and the time loop spell she had cast on him.
He had to deal with that first before facing Barrett and Edward's threat.
Dallas had just simply told Ember that; "Her brothers were vexed at him because he decided to take her with him against her will." And, she had nodded to that and excused herself.
A few minutes later, he was left alone with his thoughts.
Caleb had asked Dallas to come over by sunset. They had to do the spell as soon as the sun fades off.