A/N: Hello! Before you start to read, I would just like to confirm that yes, this is a Seblaine story. Klaine are together in it at first, but they are not the main focus. :) Have fun!
"Blaine."
Blaine loved nights like this. Although it was summer, Kurt had some mysterious technique to keep his room at a perfect temperature, and the lack of heat meant Blaine was free to cuddle up to his boyfriend. He was a light sleeper, but when he had Kurt's head laying softly on his chest and strong, pale arms wrapped around his torso, waking up wasn't something he really minded. In fact, he almost liked it, and as he adjusted his own arms around his boyfriend, he sighed happily.
Only to have the other boy squirm away from him.
"Blaine."
"What?" Blaine replied, his voice drowsy in his half-asleep state. He opened his eyes to see Kurt's wide and alert, looking up at him with a weird sense of urgency. It worried him; Kurt didn't let anything disturb his sleep.
"I think there's someone downstairs," Kurt whispered, worry seeping over his features.
"It's probably just your dad," Blaine murmured. "Don't worry yourself."
"I can hear my dad snoring from his bedroom. It's not my dad."
Blaine looked at Kurt carefully, realizing this wasn't a good time to call him out on being adorable at all but almost couldn't help himself. He'd never known Kurt to be so paranoid, and started to think that maybe the scariness of going all the way to New York was finally hitting him and making him anxious when he suddenly heard a clutter downstairs. The playfulness in his expression dispersed, silently communicating the same uneasy expression as Kurt.
"We should call the police," the taller boy whispered, tightening his arms slightly around Blaine. Blaine tried his hardest to comfort him, stroking a hand through his hair under the pretense that Kurt would probably choose comfort over the state of his hair right now. Probably.
"Don't you think that's a little drastic?" Blaine asked, not liking the expression Kurt was giving him that demanded to be right. "We don't know that it's a burglar."
"Or a murderer?"
"Or a murderer." Blaine hesitated. "Maybe we should check it out first? As good a story it would be to get the police in on a stray cat, or Finn mysteriously appearing in your kitchen, it might anger the authorities a bit."
Kurt shuffled uncomfortably, clearly not happy with the idea. If Blaine wasn't so conscious of wasting people's time, he'd happily bother the police and whisper little comforts to his boyfriend until they came, but that just wasn't him.
"We can wake your dad if it'll make you feel better?"
"No," Kurt said immediately. "I don't want him… His heart…"
"Okay," Blaine whispered, pressing a soft kiss to his forehead. "Then I'll go. You stay here."
Kurt shook his head. "We'll go together. I'll take my phone and have 911 ready dialled. And you can take one of my dad's golf clubs for defence. Just in case."
Blaine nodded, knowing deep down there was no way he'd be able to use a golf club as a defence but would take it anyway, just to make Kurt feel better. Silently, the two of them clambered out of bed, Kurt immediately taking his phone in hand before slowly cracking the door open. After checking and double checking, finding no apparent murderers hanging out on the top floor, Kurt and Blaine ventured out into the house. Kurt tilted his head towards the golf clubs at the top of the stairs, and Blaine nodded, going ahead in order to arm himself with a 7-iron and take the lead of their stake out. As they crept down the stairs, eyes squinting in the darkness, Blaine felt the hairs on the back of his neck prickle as subtle chopping noises emitted from the kitchen. He turned to look at Kurt, who was staring back at him fearfully but urging him forward. Now, it was Blaine's turn to want to call the police.
As they reached the first floor of the house, tip-toeing down the hall and peeking into the kitchen, the both of them froze. Standing with his back to them was a tall man, maybe just a bit taller than Kurt, focused on cutting whatever it was in front of him. The couple grimaced at the unapologetic noise of the steel knife hitting the chopping board.
"He has a knife," Kurt breathed as if Blaine hadn't already absorbed that part.
"I can see that," the shorter man replied, anchored to the spot in apprehension. "What do you think he's cutting?"
Kurt looked at him for a second. "Find out."
"What?"
"We need to make sure it's not… An arm or something."
"Why would it be an-"
"Just find out," Kurt snapped, taking Blaine by the shoulders and moving him forward. "You have the golf club."
"He has a knife."
Kurt continued to steer Blaine forward, and the curly haired boy had no chance but to hold the golf club out in front of him as they advanced. It didn't become any more obvious what this mysterious guy was cutting up, but he did become alarmingly still, the knife held out in plain sight. A lump lodged itself in Blaine's throat as his eyes locked on it, Kurt's lips right in his ear whispering "Oh my God". Blaine realised he had no choice but to attempt to knock the intruder out, and with the cold 7-iron clutched tight in his shaking hands, he began to get closer, raising it above his head. But just before he could swing, the man turned his head slightly, causing Kurt to gasp and grab Blaine's shoulder.
"Blaine, stop!"
The trespasser whirled round, knife still in hand as he stared at them both with mild shock, nothing like the explosive terror on Kurt and Blaine's faces. His green eyes, dull in the lack of light, took them in with slow growing amusement, and a smirk grew on his face, tracing the line of the golf club Blaine had been seconds away from hitting him with.
"Now, really, Kurt," the boy murmured, his voice somehow smooth and rough at the same time. "Is that any way to greet your brother?"
Blaine stilled, turning to look at Kurt and finally lowering his so-called weapon. His boyfriend looked back at him with the guiltiest expression Blaine had ever seen him produce.
"He's not my brother," Kurt muttered, his eyes shifting to the new addition. "He's my half brother."
"Whatever, we're still unfortunate enough to share a bloodline," he shrugged, still smirking. Kurt sighed.
"What are you doing here, Sebastian?"
"Aww, did daddy not tell you? Don't be too sad, Kurt. I'm sure he still likes you best."
"Sebastian."
"You haven't changed," he smirked. "But fine. I'm coming to play happy families with you for a while."
"You're staying?" Kurt said through his teeth, and Blaine was sure he could literally see fire in his eyes.
"Only until I go back to Dalton. Sorry, Kurty. You only have me for the summer."
"Dalton?" Blaine perked up, any nervousness lost to the excitement at the topic of his old school. "That's where I used to go!"
"I don't believe with been introduced," Sebastian said, his eyes raking over Blaine. It would've made him feel uncomfortable if he wasn't so intrigued.
"My name's Blaine," he smiled, holding out his hand for the other boy to shake. Sebastian took it after a moment of hesitation, smiling as if everything was amusing him and striking a thousand questions in Blaine's mind.
"He's my boyfriend," Kurt added, earning a dismissive chuckle from his half-brother.
"Wait – don't tell me you're Blaine. Blaine Anderson?"
"Uh, yeah. That's me," Blaine said, feeling his cheeks heat up slightly.
"You're kidding. You're like Dalton legacy. I'm pretty sure there were talks of building a shrine of you in the choir room, you know." The glint in Sebastian's eye as he spoke had Blaine not wanting to turn away, unsure when the last time was that he'd ever been so interested in a person who was in turn, interested by him.
"You're in The Warblers?!" Blaine asked, his face completely lighting up. "I love those guys!"
"I think it's safe to say the feeling's mutual," Sebastian mused. Blaine just smiled at him for a second, realising he could talk about this with Sebastian all night but forced himself to turn to Kurt, the questions in his head too much to contain.
"Why didn't you tell me you had a half-brother?" he asked, not sounding mad at all. Sebastian folded his arms and raised his eyebrows, not failing to keep the smirk on his face. Kurt had to remind himself to breathe, his glare very close to becoming lethal.
"Sebastian has a habit of stealing my things," he finally said. Blaine sensed a warning behind the words, but the other brother seemed unfazed.
"Well maybe you should take better care of them," Sebastian said, winking at Blaine as he bit into the sandwich he was previously making on the chopping board. Kurt looked like he was ready to commit murder. "It was nice meeting you, Blaine," Sebastian added, holding his gaze for a moment with the same amused expression on his face before leaving the room. Blaine turned to Kurt and tried a smile, too astonished by the situation to know what to do.
"Well, he seemed nice," Blaine offered, looking at Kurt hopefully. The other boy just shook his head, brushing past his boyfriend and leading the way back to the room. Blaine knew, as he followed Kurt with the golf club still in his hand, that sleep wasn't going to come back to him easily that night. Not with the sudden mystery of Sebastian under the same roof.