Isaac knocked his hand away, growling at him in response. "Get your fucking hands off of me." He demanded, spinning around to stare at Marcus. "I wouldn't want to be in your bedroom anyway."
His reaction was instinctive and he didn't stop to think about the consequences and his sisters reaction to them fighting in the hallway. Pulling back a fist, he hit Marcus solidly on the cheek and used his body weight to push him back, attempting to knock him off balance.