https://www.techradar.com/news/portal-2-co-writer-jay-pinkerton-returns-to-valve

One of Valve’s most influential creators has returned to the developer-turned-publisher-turned-developer a year after leaving the company, according to PC Gamer. 

Jay Pinkerton, one of the co-writers for Portal 2 alongside Erik Wolpaw and Chet Faliszek, was spotted on Valve's staff page by a Reddit user and was later confirmed by a Valve representative to have officially returned to the fold.