The night before Kurt enrolled in Glee club, in his sophomore year, he enters in a parallel world where he is a girl and has relationships (to platonic to more physique) with several boys that she may or may not know, like the quarterback Finn Hudson (whose he later fall for), the linemen Puckerman, the two other footballer player Mike Chang and Matt Rutherford and the invalid Artie Abrams. (+Jess St. James) And the following day through the rest of the year, he spent with them, knowing that he could never be that close (or flirt with) to them as he did as SHE.

For three other years, he passes the same event just on the day to finding back the Glee club.

The next year, in junior, David Karofsky was also on his- no, her harem, with the addition of the new guy Sam Evans and a ton of warblers.

On his last year of high school, in senior, she flirt and may have affair with Sabastian Smyth (since he and she is in relationship with Blaine), got Rory Flannagan and Joe Hart fawning for her and this cute future NYU boy Chandler Kiehl.

For the last world warp, Kurt (as in Courtney) meets Hunter Clarington even though she has no reason to since she breaks up with Blaine (for no apparent reason), Adam Crawford and Elliot Gilbert.

All in all, he just notices that everytime he got a boy as a girl and once he met them as boy, the encounter is indefinitely better in the first case. Being a guy liking guys sure suck but he won't change that, being proud of who he is.

Start with Klaine but KurtBastian endgame. Set end of season 2 and in between of season 3. Clearly an AU, so not much following about the Canon timeline.

Kurt and Blaine go to see a medium to know what their couple would become with their long-distance relationship. In lieu to look in her crystal ball, the seer show them an another level of voyant. She just switch two entities from different timeline and let them deal. So, a ten years later Kurt Hummel juste appears in front of a gobsmacked teenage Blaine. But only for five minutes. He learns in that short time his boyfriend got an internship at Vogue dot com, that he attends NYADA and lives in New York... Without him. Because, in the future, Klaine isn't anymore and Kurt lives better after Blaine hurt him. The latter couldn't believe it, it can't be possible, Kurt and him are just mean to be with each other, not any other way. Yet, Future!Kurt explains him that their love may be passionnel, it didn't last in long-term even if they try really hard, in the end, they would just hurt each other. Blaine refuses to face the reality and promise that he is going to change the future and make them the perfect couple. Grow-up Kurt just smiles sadly at him.

This version of Kurt is what Kurt would have become if he end up marrying Blaine Anderson at their Brittana wedding, because their relationship is just an on and off again that breaks their heart, they divorce after two years married.

And Kurt end finding true love with someone else, that young Kurt barely meet during those five minutes.

What he knows is that he got to banter each other a lot and they are really domestic with snarky come back. Kurt has to admit he quite likes this future but is kind of confuse because it's definitely not with Blaine while he just loves him so much. For now.

That's why at beginning of the new school year, Kurt asks Blaine to transfer to McKinley. He accepts and turns out, it's a really bad idea as Blaine tried to hold him in Ohio rather than let him out. Hence ending the relationship way before the actual timeline. So snarky Sebastian met a single Blaine and got bored quickly and set his eyes on Kurt, trying to disturb him during the years and glee competition. They end up finding each other at NY with Chandler as wingman.

Canon divergence in season 2, after the locker Room scene. Kurtofsky happen after the kiss, the bullying stop and Kurt goes to New York with New Direction as canon but lose at Nationals. The Chandler debacle did happen but David just asks nicely Chandler to back off.

Then, when the couple goes to NYC, Kurt is attending Nyada and David is working as a bouncer in a club. A quite fancy one, thank you. Here, he meets Blaine who is performing time from time while Kurt runs into Sebastián more than one time in this coffee shop between Nyada and Nyu. And then one night, the four men meets at dinner, and Kurtofsky get to know those two handsome men, apparently also coming from Ohio, Westerville. Kurt slowly aknowledges them once they mention The Warblers, from Dalton and then recall some memories with Blaine, whom he did have a talk with. One thing leading to another, they start hanging out.

They try at first swapping partner. Sébastien and Kurt banter and snark like an old couple while being all cheesy and cute with Blaine. David being not the open one could just chat lightly with Blaine who is friendly with everyone and tries as hard as he can to not punch Sébastien who tends to cross the line. At least the sex is hot. 

They later find out their are eache other soulmate's.

Could be considered as continuation of this Great Work.

Having his mother as great support and female figure, Kurt is as highty as in canon but know how to defends himself thankfully to kickboxing. 

In the season 2, instead of backing off from his duet with Sam Evans, because of Finn's fear, he kept this decision mostly because his mother doesn't seem disturb. So, after the duet, the two boys grow closer and eventually end up dating. Kurt still goes to Dalton to spy on the opponent. He meets and befriends Blaine (talking about bullying -slushy- and Dalton zero-bulliying policy) and totally forgot about spying. With the help of his mother and probably of Santana, the anti-bullying is create and they maintain it mid-season three.

Sam could have end moving out with the Evans or could have stayed at the Hummel.

Either way, Blaine could still be a narcistic and controlling in a relationship, Sabastian transferred prior to the start of the third season and was as flirty as in canon... but toward girl, hence a womanizer, but being somehow intrigued by Kurt.