Kurt knew.
He had known all along, really. Known from the second Blaine and Rachel kissed back in February. Known despite Blaine's lie of reassurance. But knowing and acknowledging were two different things, and so Kurt did his best to keep Rachel and Blaine apart as often as he could.
Kurt would like to pretend that he didn't see it happen, that he had no idea, that his feigned ignorance wasn't all an act. But the truth was that he didn't want to lose Blaine and whatever small claim he had on him, so when he noticed their friendship blooming he sat quietly by, hoping it would escalate into nothing more.
But then there was Prom; and the two of them dancing and watching Rachel laugh at something he had said made his insides burn. Still, this was one of their few interactions since the Rachel Berry Train Wreck Extravaganza or whatever it was Mercedes had deemed it, and Kurt knew nothing was going on yet. They were flirty, and Rachel's eyes flickered with a hint of frustration and annoyance when Kurt came to steal his boyfriend away once more, but they were still just friends.
"Rachel and I are together again," Finn grinned at him one afternoon just before school let out.
"After that stint at Nationals; I think I can safely assume that no one is surprised," Kurt responded dryly, but smiled at his step brother regardless when Finn's face fell a little. Kurt voiced his happiness for the on-again couple and silently hoped this meant Rachel would leave his own boyfriend alone and for awhile it seemed like she did.
Everything seemed to have toned down a bit until Rachel came over unannounced one day. Kurt was in the middle of preparing for his weekly coffee meet up and shopping trip full of gossip with Mercedes and Blaine was on his way home, Finn gone at football camp that Coach Beiste had insisted they attend all summer long.
"Rachel! What are you doing here?" Kurt asked when he opened the door.
"My dads were supposed to go to the Cincinnati Players production of 'Our Town' tonight but one of them is sick so they gave me the tickets, I thought I'd see if Finn wanted to go," she told him as Blaine walked over to see what all the fuss was about. Kurt tried his damnedest to ignore the grins the two shot at each other.
"Finn has football all day," Kurt reminded her, and a look of realization almost too well rehearsed played across her features.
"Well, would you like to go with me then? I'd hate to go by myself and waste a ticket," she offered, and Kurt hesitated. Ditching Mercedes and going with Rachel would be the smart thing to do if he wanted to keep his relationship intact, because as soon as he said 'no' Blaine would offer to take her. But Blaine knew of Kurt's plans, and he couldn't think of a way around this. He could only hope that their date would be as platonic as possible.
"I have plans with Mercedes," he finally admitted. Just as he predicted, Blaine offered his services.
"I don't have plans, I could go with you if you'd like," he offered, and Kurt closed his eyes to ignore the smile of pure joy that spread across Rachel's face at his words.
"That sounds lovely," she replied, her voice almost sounding through a tunnel as Kurt tried to block everything out.
"I'll just run home and get ready, then swing by to pick you up," he offered, kissing Kurt's cheek as he swept past. Rachel didn't even bother saying goodbye to Kurt as she walked to the driveway with Blaine, planning their night.
Blaine didn't call that night as he had promised, and from what Finn said he didn't hear from Rachel. Finn wasn't concerned, and Kurt didn't want to go through all the reasons he should be, so he sat staring at his phone waiting for it to ring or alert him to a new text message. It never did.
The next time the four of them hung out, Kurt was all too aware of how everyone was situated. They ended up doubling to go see the newest Harry Potter film, Rachel blushing fiercely when Blaine told her she made a beautiful Hermione and Finn looking confused, though Kurt (who had dressed as Draco) supposed the look worked for the tall Cedric Diggory Finn was supposed to be portraying. Blaine, as Harry, sat next to Rachel in the theater, and at one point Kurt was sure he saw the two holding hands.
As summer went on Kurt's suspicions rose. Finn lay truly ignorant of what was going on, but Rachel and Blaine sat a little too close, glanced a little too long, and laughed a little too often when they were all together. And then, one day, Blaine told Kurt he couldn't make it out because he had plans.
"You're not hanging out with me so you can spend time with Rachel Berry?" Kurt clarified on the phone.
"We are friends Kurt. You go off and hang with Mercedes all the time, how is this any different?" Kurt bit down the response he wanted to use-it was different because there was nothing going on between them and that they had never even begun to have any sort of sexual attraction to the other-and Blaine sighed. "Look, we'll hang out tomorrow or something," Blaine promised, shooting a quick "love you," before hanging up.
Kurt knew then that something had definitely changed in his and Blaine's relationship as well as Rachel and Blaine's. But without evidence, which Kurt was not about to go looking for, all he could do was sit idly by and hope he was wrong.
He did his best to keep Blaine distracted from Rachel and focused on him. Their make out sessions turned into more, and when Blaine asked about the sudden change all Kurt could respond with was "I'm just ready now," which was true to a point. The fact that he hoped sleeping with Blaine would prevent his boyfriend from sleeping with Rachel went unsaid, haunting him late at night when he was painfully aware that it probably wasn't.
He found out his efforts were going to waste one afternoon as he cleaned out his closet, overhearing Finn and Rachel fighting in the bedroom next to his own. "Rach, we haven't so much as made out in like a week, how the hell is there a hickey on your hip?" Kurt heard Finn accuse from the next room over. He sighed, sliding down to sit on the floor as he prepared to listen to their argument, bracing himself for the worst.
"It's not a hickey Finn, it's a bruise," came Rachel's calm reply, and Kurt could just picture Finn shaking his head.
"No, Rachel I've seen both bruises and hickeys on your body. That is not a bruise."
"Finn, listen to yourself, think of what you're accusing me of," Rachel sounded frustrated, Kurt would have been impressed by her performance had it not been a cover up of her rendezvous with his boyfriend. "Who have I even seen this summer aside from you, Kurt and Blaine?" Finn remained quiet for a minute, under the delusion that the two other boys mentioned were as far from threats as possible.
"It still looks like a hickey," Finn said, but his voice was lower, falling into the trap she was setting for him.
"I bumped my hip on the railing the other day," she repeated, and soon after they stopped talking, and Kurt went back to his task. His mind wandered to why he let this happened, how Blaine could tell him how much he loved and cared for him and then turn around and whisper the same things to Rachel. It was torture, it almost hurt too much, and yet he continually let it happen.
Everything finally came crashing down, his worse fears coming into being the Saturday after school started. He had gone over to Blaine's house unannounced, hoping to surprise his boyfriend, and knew as soon as he pulled up what he was going to walk in and see. He walked past Rachel's car, breathing deep to steady himself as he entered the house, heard them when he started climbing the stairs.
He stood outside Blaine's door for a minute, his vision of a future far away from Rachel with a pretty house filled with pretty things evaporating when he heard Blaine growl Rachel's name. He took another breath, swinging the door open and being greeted with the image of Blaine practically ravishing Rachel, a look of pure bliss on his face that even Kurt had never seen. It took a minute or two for the pair to notice Kurt leaning in the doorway, Rachel letting out a loud squeal as she tried to cover herself with a sheet, falling to the floor as Blaine sat there, confused and alarmed.
"Please, don't stop on my account, it's not like you have before," Kurt snapped, and now Blaine looked even more confused.
"It was a one-time thing, an accident, we didn't mean to-" Rachel started rambling before shutting up at Kurt's glare.
"Please. This has been going on for awhile."
"You've known," Blaine said simply, and Kurt nodded sharply. "If you've known, why haven't you said anything?"
"Because I didn't want to lose you," Kurt replied just as simply. "But now that I've been faced with the ungodly image of you two actually doing this, I see now I was being nothing short of delusional."
"We could work this out," Blaine feebly tried, but Kurt rolled his eyes.
"No, we can't. How many times were you thinking of her when you kissed me? When you grabbed my hips and said you loved me?" Kurt challenged as words he didn't even realize he wanted to shout pouring out of him. "How many times did you want to scream her name instead of mine?" Blaine looked at his hands, his face colored with shame. "That's what I thought." He walked towards the door, not turning around to let Rachel know that she should get to Finn before Kurt does, feeling like a weight had been lifted off his shoulders, like he was coming off of a high he hadn't even realized he was on.
It wasn't until later that night that he realized he actually missed the feeling of having any part of Blaine.