Cyril Arwell was the son of Madge and Reg Arwell and the younger brother of Lily Arwell. He loved big words and astronomy, and often used his telescope to look up into the sky. When he met the Eleventh Doctor in December 1941, he was taken immediately by his kindness and wonderful gizmos throughout the house. He looked into the Christmas present the Doctor gave him, leading to the planet of Christmas trees, where the populace wanted to use him as a vessel for their life force.

_{Biography from the TARDIS Data Core article, licensed under CC-BY-SA}