Remember that badass First Order Stormtrooper that kicked Finn's butt in "Star Wars: The Force Awakens" and was affectionately called "TR-8R" by fans because he shouted "TRAITOR!"? Well, Star Wars.com finally sheds light on his identity... And his name is FN-2199, or "Nines" for short!
Apparently he and Finn, known by his Stormtrooper designation FN-2187, were squadmates, and much of hist backstory is told in the prequel novel "Before The Awakening". Nines is depicted with red hair, and belongs to "riot control", which explains his proficiency with the "Z6 Baton" he used to best a lightsaber wielding Finn during the film. Though he got shot by Han Solo, fans have been clamoring for this unlikely trooper to return... Hopefully he will in the next Star Wars films to come!