Walter was a neighbour of the Collins family and a friend of Devina Collins.
The next year, Walter suffered a mental breakdown on the anniversary of her death. He hallucinated comic book character Obadiah Grimm taunting him and threw a snowglobe through his window during a fit of mania, attracting the attention of the Twelfth Doctor. The Doctor, Devina, and Jess Collins broke into Walter's house and tried to comfort him, but Walter hallucinated them being killed by Obadiah. They called an ambulance and had Walter taken to the hospital where he could recover. Devina promised to stay with him as he got the care he needed. (COMIC: Be Forgot)