In an emotional and action packed scene from Star Wars: The Force Awakens, we're introduced to a stormtrooper armed with an electrified baton who faces off with Finn. His emotionally charged "TRAITOR!" scream is well remembered by fans of the film. There's been a lot of speculation surrounding this character and his emotional tie to Finn. Was he just a spurned soldier, offended by Finn's actions or was there a deeper connection? It also seemed that the First Order trooper who streaked his own blood across Finn's helmet had a deeper connection to him as well right? I mean, it sort of started Finn down his "awakening" into turning on the First Order. Speculate no further!
Lucasfilm confirmed via StarWars.com that the baton wielding soldier is in fact designated FN-2199, nicknamed "Nines" by his fellow squad members. His character is a member of an elite riot control squad who, along with Finn, were paired with Zero and Slip during training. Slip was that dying stormtrooper who's blood is on Finn's helmet at the beginning of the film. This information all comes from Greg Rucka's book Before the Awakening, which contains three stories, each one giving just a little more backstory to Finn, Rey, and Poe Dameron.
I think it's possible we could see Nines again in the future, or perhaps even Zero coming to get Finn for some revenge? Nines could've survived the blast from Chewbacca. All in all, I love this backstory and I love how it's used in the film. It's set up quite nicely for perhaps some backstory flashbacks in future films as well.