Sort of based on the song Not Alone by Red. The title is, anyway.
Jack mildly wondered if his heart would stop before anyone could find him. The sound of it was slow and loud in his ears, beating against the inside of his skull where it rested against the carpet. The blood had cooled on his skin, leaving his skin chilled where it was soaked with crimson and resting in the stained carpet. Jack stared up at the ceiling in the dark, laying flat on his back in the center of his room with his arms spread out on either side of him. The antique blade was still in his grasp, fingers curled loosely around the polished ornate handle of the silver dagger. The edges of his vision was starting to blur, his surroundings disappearing in the face of freckles and green eyes, a phantom shape smiling at him, turning him down, walking away from him. As his skin went numb, the pale boy imagined the voice that belonged to that face, of the door slamming open and warm fingers fluttering over him, bringing life back into his body.
"Jack, why would you do this? Don't you know I love you? Come on, Jack, say something."
Jack smiled pathetically at his far fetched dreams, closing his eyes against the tears that spilled down his cheeks. The cuts had severed something in his arms, gushing blood and setting his skin on fire, burning through his veins. He wondered what Hiccup's favorite color was; maybe he didn't like white or blue, maybe that was why he didn't like Jack. Maybe he liked red. The blood was a dark liquid crimson where it smeared down his bony arms, made his clothes soggy. Would Hiccup like him better this way, painted in a color that was such a stark contrast to his pale features?
The dying teenager dreamed of Hiccup pressing their lips together, of feeling his lungs expand with warmth and his skin tingle to life where he touched it. He clenched his fingers and a fresh wave of warmth spilled over his skin. Droplets landed on his cheeks, Hiccup's eyes sparkling and glassy in the light of the moon pouring through the window. His lips moved but Jack could no longer hear anything over the humming in his ears, eyes drooping with exhaustion. Suddenly he was being dragged off the ground, light exploding around him. Thin arms held him against a brittle chest, blood smeared into green sleeves and freckled skin. Hiccup was cradling him in his arms, long fingers combing through his hair. Jack sighed, glad that at least he could be left with a peaceful illusion before the light swallowed his vision, and Hiccup's touch disappeared, the heaviness that held his limbs still dissipated; then the light, too was gone.
The brunette paced nervously, eyes swollen and cheeks stiff from dried tears. His heart beat was still a little erratic, eyes flicking to the heart monitor on the other side of the room every five seconds. Hiccup had gone looking for his cat Toothless, wandering the neighborhood when he ambled in front of Jack's house. Their dads had been best friends since before Jack and Hiccup were born, so both had a front door key to the others' house.
The freckled boy had decided to pay a visit to his friend, to see if he was still awake or pull some revenge prank on him if he wasn't. He thought his heart would stop when he cracked the door open to find his Jack collapsed on the floor, shivering and drenched in his own blood. In his hand was the old Norse rune blade his dad had given North, covered in blood. The gashes were so deep, the blood so thick it was nearly black. The teenager's lips were blue and he was hardly breathing. He heard himself speaking, anguish welling up in his heart as he tried to do something to help. He dialed 911 for an ambulance, screamed for North, performed CPR when he thought he saw him stop breathing. His skin was icy, and he was so close to death, but he smiled up at Hiccup, trying to speak his name and other things but couldn't get it out with his leaden tongue. Hiccup had gathered the secret love of his life in his arms and tried to use his own body heat to keep him warm, blinking against tears that threatened to blind him, having a death grip over the wounds to stop the bleeding while stuttering fingers combed through Jack's hair with the other, staining the snowy white strands with blood.
Hiccup refused to leave the hospital during the first week of unconsciousness. He was firmly rooted to the pale boy's side, only vacating his chair to go to the bathroom or when North showed up. Jack remained a deathly pale, dark circles under his eyes, a breathing mask hooked up to his face, an ivy providing a blood transfusion to make up for all the blood that had been lost. He hardly slept, mind plagued with blue irises drowning in a sea of red every time he closed his eyes. The week after that, he finally returned home for much needed shower and sleep, his cat Toothless never leaving his side as his mind replayed every moment over again, haunted by the image of Jack's bluish lips stretching into a smile, "Hic-.. L-lo..-" Once, his dad had to pry his arms off of himself, fingers leaving red marks where he held onto himself so tightly he nearly left bruises. By the third week he was going back to school, mind not catching a single word that left anyone's mouth, going to see his best friend in the hospital every day after school.
Half way through the fourth week, Jack finally woke up. His hand came up, searching blindly for something, eyelids fluttering as his heart rate increased. Hiccup lurched out of his chair and grasped the hand desperately, watching his pulse even out on the monitor as blue irises found green ones before they unfocused again. North had ended his shift at work early to come see him, the breathing mask removed and Jack rasping out words by the time he got there. Hiccup was slouched over the bedside, tears soaking into the sheets where his head rested on Jack's stomach, shoulders shaking silently. He was discharged from the hospital two days later, the brunette refusing to leave his side, their hands clutched together at all times.
North was too stricken to notice the unusual closeness between them. Hiccup stayed in Jack's room the following three days after his release. The brunette managed to pry the real reason behind his self mutilation, kissing the blue-eyed teenager until he gasped for air and clutched his body close to him, sobbing quietly in relief while Hiccup held him until he fell asleep.
The wounds healed into scars and the panic faded. Hiccup loved him until things were just about normal again, the two exchanging jokes and teasing easily in the day, taking turns making the other shake apart beneath them at night. Hiccup eventually stopped having nightmares about red-stained carpets and silver knives, the light danced in Jack's eyes like it never did before. The wide dark lines marring Jack's forearms became a symbol of their love branded into his skin, Hiccup imitating the harsh crisscross patterns in a tattoo over his heart. The ragged lines that had once ripped apart Jack's skin were now what held them together in rougher times; when Hiccup's father passed, when Jack left his dad to move in with Hiccup for college, when they struggled financially and in their relationship. Hiccup traced the pattern every night before bed, when he and Jack graduated college, when they got married and adopted children; until Toothless kicked the bucket and his hair grayed at the temples, and their grandchildren traced the invisible patterns over their hearts every night like a good luck charm, trusting the power of love to never lead them astray.