Dean's first instinct when he heard her scream was to take action. For all he knew she could be fighting off an attacker in there and he could only think of getting in there. He started turning the door knob and throwing his weight against the door over and over again. The adrenaline coursed through him so fast that he probably could have ripped the door off its hinges right then and there if he could have gotten a good hold on it. "Shannon!" he shouted. "Shannon, are you okay?"
There was a loud sound from the other side of the door and Dean stepped back, prepared for anything to come shooting out of the opening. He stepped onto the balls of his feet, arms out defensively, as he tried to catch his breath. But all he saw when the door was thrown open was Shannon. He registered relief for himself and then the deer in the headlights expression she wore. And she was shaking.
"Oh, Shannon. I'm so sorry," he said and relaxed his body, taking a hesitant step toward her. He wasn't sure if she believed it really was him or if she believed he had played a joke on her still. He wanted to reach out and touch her face or pull her into his arms and hold her until she stopped shaking but instead he stood there, looking for some sign that she wasn't going to bolt.