Gunner looked at Anna as she looked at her phone. He was preparing to head to the Moroi dorm, since Anna couldn't, when Sebastian popped up behind Serena. He looked at the girl as it looked like her eyes were going to bulge out of her skull. He watched as every muscle in her tensed but despite her clear discomfort, she didn't move or say anything to stop Sebastian. 

Gunner was about to tell Sebastian to leave her alone, because clearly she wasn't, when a Moroi joined them and Gunner bit his tongue. He nodded to the girl and gave a wave when Anna introduced him. He glanced back warily at Serena, he decided not to say anything. If this girl was going to be a guardian, she was going to be in desperate need of a back bone.
~
Serena looked at the two of them as they worried about Sebastian, when a voice popped up behind her. She already tensed at the sound but her eyes widened and her body went rigid when she felt a chin on her head. Her hand started to fiddle with the sleeve on her shirt. Anna asked him something about self-medicating and Serena gave her a confused look. She had heard stories about Spirit, the fifth element wielded by the Queen. However, she had never met anyone who had it. Or someone she was aware had it. She wondered if Sebastian had it as well... The stories of the effects of Spirit had made their way to Santa Catherina's as well. She didn't have a chance to ask nor hear his answer before a Moroi joined them. If her body could, it tensed further. She wasn't normally around this many people she didn't know. She was rarely in the presence of two Moroi and never had any of them even thought of placing their chin on her head.

She was scared to move her head, in fear that Sebastian's chin would cause some of her neck to be revealed. She wasn't exactly at the state where she could openly hit him, even if a elbow to his side would make him back off. Instead, she kept her eyes straight ahead and gave a shy wave when Anna introduced her.