Robdam is a portmanteau or mashup name given to the pairing of Supernatural writers Robbie Thompson and Adam Glass in a romantic or sexual relationship in slash fanworks. The pairing became popular soon after both joined Twitter in early 2013 and were unable to hide their epic erotic bromance, which fueled the imagination of their legion of fans.
Other mashup names including Adobbie, Glompson and RobAss are also occasionally used.
Robbie/Adam fic is a niche pairing in the real Person fanfic (RPF) genre which is dominated by J2. However it is a prestigious pairing, with writer S.E. Hinton expressing interesting in writing about it. Source.
The pairing had a much welcomed revival in 2019 when Robbie joined Adam Glass on his "Teen Titans" series for DC Comics.