Sometimes, she can’t sleep at night. She misses the quiet hum that was the TARDIS. It was always there, a slow, steady murmur that let her sleep peacefully, despite the horrors she had faced with the Doctor . And him being there made all the difference. Having someone who had faced more than you had gave a comforting feeling, one that told you that all was not lost.
She had tried to simulate that hum before. She tried playing music before going to sleep, and humming under her breath. Nothing could replace the comforting sound.
Sometimes, she can’t sleep at night.