Xoco was the mother of Tochtli. Her husband was killed by the bonepuppets.
Xoco and her husband were spies for the Aztec empire. Xoco used her psychic abilities to help the Doctor defeat the bonepuppets.
When Tochtli was born, the Doctor helped to deliver him. At Xoco's request, he took the umbilical cord and buried it in a battlefield. (PROSE: Nobody's Gift)