After his first episode, Sterling Brown's friends called him and repeated their favorite line to him: "Dead man's blood, bitch."
According to series creator Eric Kripke, Gordon was originally going to learn about the hunter Sam killed while possessed and use it to convince more hunters to turn against Sam. This was intended to be a story arc stretching over multiple episodes. However, Sterling K. Brown was contracted for the Lifetime Television series Army Wives, and Lifetime would only allow him to return to Supernatural for only two more episodes. A multiple episode story arc was originally planned for season three revolving around Gordon finding out about Steve Wandell, the hunter Sam killed in Born Under a Bad Sign, and rounding up a posse of hunters to go after Sam. Unfortunately scheduling conflicts with [Sterling] Brown meant the show would only have him for two episodes, and it was decided to drop that storyline and to bring Gordon's arc to an end. - Supernatural Creator Eric Kripke Answers Fan Questions - Part II
"Walker" may be another gun-related name, in this case referencing the Walker Colt revolver.
Gordon's character may be a reference to Charles Gunn from Angel, also a vampire hunter of African descent whose younger sister was turned into a vampire, forcing the hunter to kill his own turned sister.
Used to frequent the Roadhouse around 2000-2001. Had some conflict with Jo and Ellen. This was seen in Jo's Journal. In Bloodlust, Ellen warns Sam of Gordon.
Gordon keeps a hunter's journal.
He has met John Winchester.
Gordon arguably hates vampires more than any other hunter shown. However ironically, it did not take long for him to feed on an innocent human after turning into a vampire himself.
Gordon is the first of three hunters shown to be turned into monsters: Gordon and Dean were both turned into vampires, though Dean's transformation was reversed. Garth Fitzgerald IV was turned into a werewolf which is incurable, but has learned to live with it and adapt, unlike Gordon and Dean who both wanted to die after being transformed, albeit after killing Sam in Gordon's case.