Instead of retreating, Sarah was holding onto him. She wasn't running away. She wasn't going anywhere, and the flickering thoughts in her mind said as sure as anything that she wasn't planning to leave anytime soon. Ever, if she could help it.
Rather suddenly, Peter was overwhelmed. Her ease with his multitude of abilities had already seemed unreal, and part of him had suspected if she really didn't see this all as a game. A puzzle to figure out, or a pattern to unlock. That there would eventually be a puff of smoke and a shout of 'Surprise!' after which they could go about leading and living out their lives; maybe normal, maybe peaceful, likely neither, but finite and together. It was startling to realize that she understood. That this was no fiction, but the cold, hard facts of his life. That the potential immortality was a curse, a terrible curse for someone who put as much stock in people as he did.
She understood. And she didn't run from that realization, but embraced it with all the force she could muster. And Peter trembled with his own realization of the depth of her love. His hand sank into her hair, face pressing into that spot moulded for him between her neck and shoulder. There were no words he could say or think with any clarity but I love you, and the gratitude and love radiating in his thoughts left even those words far behind.