The watch is useless, but River keeps it anyway. Even though it runs normally, it has no meaning to her. Her personal timeline isn't stretched by the ordinary rhythms of a watch's second hand, but by the wobbly spinning of a child's top.

Sometimes, she takes it out of her pocket and runs her fingers over the engravings, intricate criss-crossing circles in a language she can sometimes read. She remembers the stories he told her—this watch once held his Time Lord consciousness, his true self, when he hid as a human. He had brushed over the details, but she was already hearing more than he said. Someone had gotten too close to his lonely hearts, and he didn't want to risk it again.

In one of their very first trips, the Doctor told her that the Greeks had two words for time—chronos and kairos. Chronos was the root of words like chronology, for ordinary time, time that began and ended in the proper order. But kairos meant historical, legendary: an event that twisted timelines, not just marked them.

The word echoed in her mind like the first time the StormCage doors closed behind her. Maybe that's why he gave her the watch the next time he came. On one hand, it was chronos, just another measuring device, but also a taste of karios. The twisted, winding life of two time travelers, where chronos was rare, and kairos marked each meeting.