Kurt-Sebastian Relationship

The Kurt-Sebastian Relationship, also commonly known as Kurtbastian, Hummelsmythe, Sekurt or Sebkurt is the previous rivalry and friendship between Kurt Hummel and Sebastian Smythe, over Kurt's boyfriend Blaine Anderson.

Overview
Kurt Hummel first meets Sebastian Smythe in The First Time. He is immediately upset in the way Sebastian is flirting with his boyfriend Blaine Anderson and asks Kurt questions in a passive aggressive way. Sebastian offers fake ID's to the gay bar Blaine declines but Kurt surprisingly accepts, wanting to show Sebastian that he can be "fun" and "out-there" like him too. At Scandals, Kurt starts to dislike Sebastian even more when he dances with a drunk Blaine. Sebastian continues to pursue Blaine through Hold On To Sixteen and Michael, continuing the rivalry between the two, one of them including Sebastian meaning to throw rock-salt-filled slushy at Kurt instead of Blaine.

The First Time
Sebastian and Kurt first met in The First Time at The Lima Bean after Sebastian tries to make a move on Blaine by stating that his 'whole bashful schoolboy thing' is 'super hot'. When Blaine tries to explain that he has a boyfriend, Sebastian tells him that it doesn't bother him. In a fluster, Blaine says that he really cares about Kurt and never wants to mess his thing up with him and that he's really great when Kurt comes over and asks, "Who's really great?" thus kicking off the rivalry.

Later in the episode after, Sebastian invites the pair to Scandals, the local gay bar. Kurt tries to butt in between Sebastian and Blaine on the dance floor so he can dance with his boyfriend. Kurt gets angry at Blaine after they leave, shouting about how he hated that Blaine had spent most of the night 'dancing with another guy'. During the school's rendition of America from West Side Story, Kurt spots the Dalton Academy Warblers and, most importantly, Sebastian in the audience, there to see Blaine star as Tony.

Even though Blaine clearly states in The First Time that Sebastian means nothing to him, Kurt is obviously still worried that Sebastian has some plan to win Blaine over.

Hold on to Sixteen
In Hold On To Sixteen Blaine and Kurt have a scene in the The Lima Bean where Sebastian comes and joins them, flirting with Blaine straight away. Blaine leaves for another coffee and Kurt tells Sebastian exactly what he thinks of him, smirking, "I don't like you," to which Sebastian replies, "Fun, I don't like you either." The rivalry really kicks off in this scene where Kurt says everything that is on his mind. Sebastian then gives Kurt a piece of his own mind and boldly tells Kurt that he'll have Blaine and a Nationals trophy by the end of the year whereas Kurt will have nothing. Kurt then responds that Sebastian "smells like Craigslist."

When New Directions perform at Sectionals, Kurt spots Sebastian in the audience during their rendition of ABC. He is seen standing, cheering, and clapping along, but he is clearly there for Blaine which worries Kurt even more. Even during the performance, Kurt shoots Sebastian an angry glare.

Michael
In the beginning of the episode, Sebastian sees some members of New Directions at The Lima Bean and tells them about the changes he made to The Warblers' setlist for Regionals to include Michael Jackson after hearing of the New Directions' plans to do so. He insults Kurt by saying, "Oh, hey, Kurt. I didn't recognize you. You are wearing boy clothes for once," and Kurt frowns in annoyance.

After Blaine is hurt from the rock salt slushie that Sebastian intended to be for Kurt, Kurt speaks to Santana about Sebastian. He states, "I take a lot of crap from a lot of people, but I refuse to take it from Sebastian, the criminal chipmunk....After what he did to Blaine... I really wanted to hurt him." Still, Kurt pledges not to hurt Sebastian, because he has fought against violence for too long and he "has to take the high road."

In a scene that didn't make the episode, Kurt with Blaine, Santana, Rachel, and Artie walk down the halls of Dalton and watch the Warblers perform their interpretation of Michael with his Jackon 5 song, I Want You Back. Although all of the members looks disgusted, Kurt looks the most angry, even giving him some strong "death glares." However, throughout the performance, Sebastian pays very little attention to him and instead focuses on Blaine, which makes him even more angry.

On My Way
Kurt and Rachel are looking at wedding magazines, looking over different wedding dresses while sipping coffee in the Lima Ben. Sebastian surprises them and hands Rachel an 'engagement gift' which turns out to be a photoshopped picture of Finn, naked and in high heels. Sebastian threatens her to draw out of the competition or else the photoshopped photo will be uploaded on the internet. During this heated situation/conversation, Kurt and Sebastian constantly throw offences at each other.

After when they hear of Karofsky's attempted suicide, at the Lima Bean, Sebastian calls Santana, Brittany, Blaine and Kurt over. Santana tells him that the blackmailing and everything his doing has got to stop and he agrees. He informs them that all the Finn photos have been destroyed and he apologises about his wrongdoings. Kurt however silently mutters to Blaine and tells Blaine to 'wait for the punch, because you know it's coming.' But Sebastian breaks in and says the Warblers are running a Lady Gaga's Born This Way foundation/charity and dedicating the performance to Dave Karofsky.

The feelings between Kurt and Sebastian has lightened up as well as the feelings between Blaine and Sebastian.

Trivia

 * Sebastian - according to Kurt - "smells like Craigslist" and has a "smirky meerkat face."
 * In Sebastian's opinion, Blaine is too good for Kurt.
 * Both boys have been/are in the Dalton Academy Warblers.
 * Both boys have been/are attracted to Blaine, but only Kurt has kissed him and had sex with him.
 * Grant Gustin, the actor of Sebastian, ships the couple.