Eric had taken it upon himself to research Alcide's life thoroughly when he'd press-ganged the werewolf into working for him, of course. It never hurt to have blackmail material on someone who was working for him against their will in case they needed to be kept in line.
He saw the punch coming and tried to dodge it, but there were a combination of factors working against him: he was slower in Alcide's body than in his own, and Vala had recently had his blood, making her stronger and faster than the average human. Alcide's aim was true, and the punch meant for his nose connected with the right side of his face despite the fact that Eric had tried to get out of the way. He was certain that he would have a black eye; it fucking hurt.
Loosing a roar of outrage from deep in Alcide's throat, Eric launched himself at the other man, knocking Vala's smaller frame easily to the floor. He was past the point of worrying about hurting Vala; she wasn't in her body to be able to feel it, and when they did manage to switch back, he could always heal her with his blood.
He pinned Alcide to the floor on his stomach, one knee digging into his back to hold him there, hard enough to bruise. He grabbed one arm in his large hand and twisted it behind Alcide's back, trapping the other arm against his side with his other knee. He gripped Vala's long hair with the other hand, tugging on it to pull Alcide's head back at a painful angle. "I told you not to call my lover a fangbanger," he said, his voice low and dangerous. "Take it back," he ordered, "or I'll break your fucking arm."