Reason of attack?
Sam was in a panic at what to do after seeing Quinn lose that much blood. He wondered if something strange might happen because of his unique body or if he would just die. He knew vampires were reliant on blood, and even though he himself was still human at the moment, he couldn't just give some of his own in front of Nate and Blip.
"Come on, where is he, where is he?"
And that's when Sam finally remembered. Fex was currently at the ship docks waiting for him. Today they were meant to go out and head to the large spaceship.
After finding Fex and explaining what happened, Fex rushed off to where Quinn was and were the first ones back. Sam used some excuse to get Nate and him to both leave, and when they did, he started to pour blood into Quinn's mouth from his own blood flask.
He started to respond a bit better, and now the wounds around his arms were starting to heal.