First attempt at fan-fic, so please don't judge me to harshly. It even has two different endings so you can choose your favourite one.
It's a generic Sam/Kurt story.

"Hey buddy," Sue Sylvester exclaimed in that dagger through your chest kind of way she always addresses Will Schuester as she strolled into the glee choir room in her red track suit disrupting a vocal training exercise. "Heard your glee kids are getting picked off like the ten little Indians. That's an all time low even for you."
Mr. Schuester gritted his teeth. One day he'd find a way to make her shut up. But sadly this time (as many other times before, but he'd never admit it) she was right. Even Santana looked uneasy and Mercedes shot the cheerios' coach deadly glares, but as usual they did not even dent the Sylvester Armour of pure Idontcareonite.
"Puckerman might be out of juvie before sectionals, but that still leaves you with only eleven kids," Sue continued. "Let me refresh your memory…"

As Sue picked out the rule book and cited the part where a glee group had to consist of at least twelve members and as she snapped the book together she addressed the glee club with a question.
"You know what that means kids?"

As usual Brittany was quick on the uptake and answered.
"That you will be joining us, coach Sylvester?"
For a second Finn looked like he was going to faint in panic before Rachel poked him in the ribs with her elbows to make him realize how much that would NEVER happen.

With a confused look on her face Quinn raised her hand and everyone's attention shifted to her.
"What's happened, Mr. Schue? I was visiting my sister the last few days, and when I came back everyone was so sombre…"

Mike and Tina simultaneously opened their mouths to tell her, but were cut short by Sue.
"I'll tell you what's happened, Q," she said with a serious voice. "Your good for nothing teacher here turned a blind eye once to many…"
"Karsofsky and Azimio kicked the crap out of Kurt," Artie cut in and earned himself a glare from Sue that almost sent him running despite being in a wheelchair.
"Yes, roller-boy," Sue continued. "And as Will here was to busy curling his hair with power drill to put an end to it, the gay boy got fed up and transferred schools."

Quinn's beautiful eyes turned wide, as did Sam's beside her.
"He cleaned out his locker before, and was going to get some of his stuff from the auditorium dressing room," Mike put in while Tina nodded to confirm the truth in the statement.
"He's… not coming back?" Sam asked slowly while Quinn swallowed hard. She'd really liked Kurt. Not only because he could out-sing Rachel and annoy her.

"Fellow Glee-clubbers," Rachel said as she clapped her hands together and stood up. "As I always have a song prepared for every occasion, I have a little something here to sum up what we're all feeling right now."
As everyone else was staring wide eyed at her back she approached the grand piano and stuck her sheet music to Brad who just shook his head at her.

"Restrain yourself, Streisand," Sue rolled her eyes. "This whole mess reminds me when a certain ginger crazy with eyes like a hentai tentacle victim decided to quit her job and some nut-job with hair like a bad crème-brûlee ran through the entire school to stop her…"

Will covered his face with his hand as an uneasy smile hinted on the lips of the glee kids and a strange tension filled the room.
Santana arced an eyebrow as she followed the gaze of Sue and blinked when she started to understand. Mercedes shot her a glance and nodded. You could see the cogwheels turning in Rachel's head as she was trying to figure out why she should make a dramatic, slow motion, dash after Kurt and stop him just before he got on the bus. Finn looked completely confused and Brittany was clearly thinking about kittens. Quinn leaned back and looked at the person on her left while thoughtfully pursing her lips.

"… after that I put up trip-wires all over school, but Figgins made me take them down as some kids apparently managed to get hurt by them." Sue fell silent and shook her head. "I jammed the dressing room door behind him, but he's probably gotten out by now. The game is on, Tramp. The Lady has left the building. I don't know how much clearer I can get…"

Even Will looked amazed at Sue when things dawned on him. One by one they all turned their eyes in one direction. Sam cringed a bit and looked quite bothered and uneasy.
"What are you waiting for, idiot?" Quinn boxed his shoulder. "Go!"

For a moment Sam turned pale as ash and looked like he was about to either faint or tell them all to sod off. Then… He bolted.

"Yes!" Artie said as Tina and mike took each other's hand expectantly. The tension in the choir room turned to anticipation for when Sam would return with their diva.

Sue actually smiled as Sam disappeared through the door.
"Seems like dyslexia can extend to the heart as well…"
Then she shrugged and started for the door.
"Well, I'm off to get that heap of junk Will calls a car towed."

[Ending 1]
The auditorium dressing room was empty when Sam got there. The lock had been jammed but picked with the help of a wire coat hanger. In the middle of his disappointment he couldn't help being impressed by the clever ingenuity of the escape.

With a growing lump in the pit of his stomach Sam started for the bus stop while cold fear started to claw at his heart. How come everyone but him had seen it coming? As he left the auditorium he could see the bus closing in on the bus stop. He might still make it. He had to make it. He just had to.

Across the parking lot of the school he could make out Kurt in that hat he'd worn that time when he dumped him for the duet. The final "uh-huh" echoed in his mind as he ran for all he was worth losing sight of the bus stop as he had to round the recycling station and the dumpsters.

Panting Sam reached the bus stop just in time to see the bus glide away, the red rear lights glaring at him like open wounds. With cold realization he watched the bus turn a corner and he could feel the tears swelling up, running down his burning cheeks.
Too late, he was too late.
"Please don't go," he whispered to himself. "I need you…"

[Ending 2 - Alternate ending]
The bruises didn't hurt as much as the humiliation and transferring to another school would be for the best. Still Kurt couldn't help but feeling empty as he folded the last pieces of clothes he had stored in the auditorium dressing room. With everything packed he grabbed the door handle and realized the door was locked.
This was the last straw. He was so damn done with this place. Done with Karsofsky and Azimio. Done with pregnancy drama. Done with back-up vocals to the lesser beings. Done with Finn breathing down his back. Done with that stupid, annoying jock with the beautiful eyes. Especially with him.
Frustrated he banged the door as hard as he could with his fist and winced as it hurt. Since nobody stops the Hummels he grabbed a wire coat-hanger and let the shirt on it, he was pretty certain it was Rachel's, drop to the floor. With angry determination he started to bend the coat-hanger into a makeshift lock pick.

Suddenly the key rustled in the lock and with a click the door opened. Kurt stared at the out of breath appearance that was Sam.
"What do you want?" Kurt asked, still a bit agitated after getting locked in.
"I heard there was a princess locked up in a castle here somewhere," Sam said, smiling that damn smile that always made Kurt's heart skip a beat.
"I'm sorry, but your princess is in another castle…" Kurt answered quietly as he put the coat-hanger/lock-pick down.
"Nope," came the reply slyly, followed by a more quiet. "You're right here…"
Kurt was for once at a loss for words as Sam gently put a hand on his bruised cheek and looked him into the eyes.
"Please don't go," he whispered to Kurt. "I need you…"

Oh I'm falling into you
This dream could come true
And it feels so good falling into you