Summary: Jace volunteers to be a guinea pig when Magnus invents a spell to protect Nephilim from demon possession.

Author's Notes: So very grateful for the positive feedback the first story received! If that one made you cry, then this one might kill you, so, fair warning! Grab some tissues, turn on some of Arn Andersson's emotional piano music, and enjoy this one!

Parabatai Pain
PenPatronus
Story #2
Greater Love Hath No Man

One of the millions of snowflakes falling on New York City snuck through the small space between Alec's spine and his shirt collar. Magnus saw him shiver and, with a snap of his fingers and a crack of blue magic, extended the translucent umbrella he'd erected above Clary to the rest of the Institute's roof. Alec gifted Magnus a grateful smile and tugged playfully on the sleeve of the warlock's maroon velvet jacket when he walked by.

"Done!" Clary announced. She popped up to her feet, brushed chalk covered hands down her jeans, and stepped back to examine her art by the moonlight. Magnus pressed a forefinger to his lips and traveled around the hot tub-wide circle of multicolored runes, squinting. Clary glanced at Jace for reassurance. He winked.

Magnus clapped his hands once and declared, "Magnificent sigil, biscuit! You must create a piece for my apartment." He tipped his head towards his boyfriend and asked, "How are you at drawing portraits? Perhaps of a nude model?"

A squeak from Isabelle. She covered her mouth, but that did little to stifle her laughter when Alec's cheeks turned as red as his fletched arrows. Jace saved his parabatai from further embarrassment by unsheathing his stele and approaching the circle like a boxer walking into the ring. "We ready to do this?"

Magnus held his hand out for the stele and Jace surrendered it. A swirl of violet, blue, and peach magic exited the warlock's fingertips and soaked into the tool. "Hop in," he said, and Jace stepped over the chalk to the empty center of the circle. "Carefully! Don't smear the chalk! The colors and angles must be exact!"

Jace held his hands up in surrender. "I didn't! I'm not!"

Clary pulled her down jacket tighter and hiked the collar up to protect her cheeks from the blossoming New York City winter. "Have I mentioned that I don't like this?"

"More than once," droned Alec, rolling his eyes. He switched his bow from his left shoulder to the right and sighed. "But—for once—Clary and I are on the same page. I don't like this either. I meant it, Magnus, when I said I wanted to be the one to test this."

"Don't trust me?" demanded Jace.

"I trust you."

"So, it's Magnus you don't trust?"

"Him I definitely trust."

"Why does he get the 'definitely'?" Jace scowled. "I'd never say I 'trust' you but 'definitely trust' Clary!"

"He doesn't trust demons," Isabelle translated for the group. Her smile looked extra white between fuzzy black earmuffs.

"Who does?" Clary pointed out.

"I mean he's worried that the demon could know something we don't, or have power that Magnus can't anticipate."

"A reasonable concern," Magnus agreed. "But! Fortunately for you, Shadowhunters, I didn't pick the spirit we're summoning at random. I chose a young demon—barely half a millennia old. Compared to the Greater Demon elders he's strutting around Hell in diapers. So, even if my new protection spell fails and it possesses Jace, it'll be easy to separate them."

Jace unzipped his black winter jacket and pinwheeled his arms, making sure that he had his full range of motion despite his thicker winter clothes. "And you'll separate us how, exactly?" he wondered.

Alec cocked a red arrow into his silver bow. "I'll aim for something fleshy and useless," he assured his parabatai, "like your ass." The whole group chuckled when Jace pouted his lips and rubbed his rear end.

Isabelle fingered the whip bracelet around her wrist. "Boys, you couldn't pay me to do this. I still have nightmares about being possessed." Izzy glanced at her brother and she could tell by how he resisted meeting her gaze that Alec had his fair share of nightmares as well. For someone so committed to protecting people, and so vigilant about controlling his own actions, the demon possession and subsequent murder of Jocelyn left him traumatized. Since then, Magnus had rallied every resource in the international Downworld to create a spell that, once embedded in a stele, would protect any Nephilim from possession. None of them wanted Alec to experience something so horrific ever again.

Jace hesitated after Magnus returned his stele. "What do I do—point it? Hold it against my skin? Keep it in my pocket?" he asked.

Magnus shrugged. "That's part of this experiment. If it's in your pocket, and the demon possesses you then—voila—we'll know not to do that!"

"Comforting. Thanks." Jace held his stele at arm's length like it was about to explode. "So, the spell doesn't need activated?"

"Think of it like a seraph blade instead of a rune," advised Magnus. "Always with you, always ready."

"But it may or may not work," Isabelle recapped for the group.

"Stop reminding me," Alec hissed. To Jace he said, "If I beg you one last time not to do this, would it change anything?"

Jace faked a sudden loss of hearing. "Huh?"

"You're insufferable." Alec meant the word as an insult, but it came out playful.

Jace grinned. "I'm adorable."

"Places, everyone," said Magnus with the panache of the film director. He, Alec, Izzy, and Clary stood shoulder to shoulder outside of the circle. Inside, Jace held his stele like a magic wand. "Putting the wards up now." Magnus snapped his fingers and a transparent veil immediately separated Jace from them. "Ceremony, incantation, fingers crossed—here we go!" The foreign words Magnus spoke sounded like a lazy combination of Arabic and French. He clucked his tongue at the end of the final sentence and stamped his left foot once as if to squish a cockroach. Ruby light glowed from Isabelle's necklace. A tornado-shaped swirl of black smoke barely thicker than Jace's arm descended from the air and wrapped, snakelike, around his ankle.

A pair of wide, aqua eyes blinked repeatedly. It looked like the incorporeal demon had just woken from a nap.

"Jace? Are you ok?" Clary squirmed at the sight of the aqua-eyed spirit slithering up his leg, across his torso, around his back, and then down his arm towards the glowing stele.

"It's working! I can barely feel it touching me!" Jace shouted over the demon's feeble grunts and barks. The smoke bumped against the wards and then immediately recoiled. "I think it's trying to possess me but it—it's like it can't find a way inside! Magnus, man, you're a genius!"

The warlock shrugged. He didn't refute the compliment.

"What does it feel like?" Izzy asked.

The shadow darted in and out of Jace's sleeves, and then circled around his golden hair, resembling a black halo. "It feels like, uh…" His face squished up like someone had just opened the dumpster behind Hunter's Moon. "Ugh, like a slimy tentacle that's—that's kissing me!"

Clary pretended to gag. Magnus snickered. Isabelle told Jace and the demon to "get a room!"

It was Alec's archer eyes that spotted the accumulated snow on Jace's shoulder. Flakes had coalesced into a thumbnail-sized drop of water, and Jace's wriggling sent it tumbling down towards the fragile sigil. Water splashed across a triangle of pumpkin-colored chalk and smeared it with a teal and green circle. "Magnus!" The other four didn't hear him over their laughter. The aqua-eyed demon suddenly slipped up towards the sky like a cloud had sipped it through a straw. A beat of loud silence—a distant echo like a door flying off its hinges—and then a roaring column of blackness descended and skewered Jace like an axe through wood. Dark smoke, tinted with a fiery neon rainbow, invaded his body head to toe. Jace collapsed onto his back, silent. Still.

All of them—even Magnus—bounced off the wards in a rush to reach Jace. Clary scratched at the veil with dull nails and screamed for him to wake up. Izzy shouted for Magnus to disable the shields, but he silenced her with a look. "I'm sorry, Alexander!" the warlock said. "The sigil was corrupted. If there's different, stronger demon in him now it could—"

"Just get him out of there!" Alec snapped. He knelt in front of Izzy and begged Jace to wake up.

Unfortunately, the thing that woke up was not Jace.

Black eyes burst open from corpse-grey eyelids. A stunned Alec fell back against Izzy's knees, palm against his mouth. Courage trickled down and out of his spine and evaporated. Two pairs of arms wrapped around Alec's middle and pulled him up and away. Izzy. Magnus. "There's no telling what demon we're dealing with now! Alexander, the moment I drop the wards you have to shoot!"

Izzy and Clary helped Alec stand and fumble with his weapons. Jace's eyes like raven's feathers bore into and through Alec, and he found himself unable to look away. The demon rose to its feet without using any of Jace's muscles. Sparks like fireflies hovered around its fingers and erupted from its lungs. A voice like a seraph sword dragged across gravel spoke Alec's name with Jace's lips. Magnus shouted for Izzy and Clary to fall back and after a brief argument, the two girls retreated to the furthest corner of the roof, blades held up defensively.

"Alec!" Magnus shook the archer's arm to get his attention. "Don't hesitate! You hear me? I know it's Jace, but don't hesitate for a second."

Alec nodded, jaw clenched. He leveled the arrow directly at those hypnotizing eyes, then aimed for the left arm. Magnus' magic swirled around the roof. The warlock counted, snapped his fingers, and hollered, "Alec, NOW!"

A quick prayer for Jace to forgive him. Alec sent the arrow.

Demon-Jace twisted as he leapt into the air. He caught the arrow, but not with his hands. The entire Institute shook when he landed on one knee, black eyes blazing, arrow clenched between his teeth. Above, Magnus' sheltering bubble exploded. Freezing, bleached confetti-like snow made them feel like they were in the heart of a snow globe. Alec summoned his courage—splinters to a magnet—and reloaded. This time he aimed at Jace's shoulder, but cocked his ring finger so that, like a curveball thrown by a baseball pitcher, the arrow would swerve. Alec was seconds—only one second away from firing.

And that was when the sensation of a thousand bee stings pricked his parabatai rune.

Alec screamed so loudly with pain that he briefly deafened himself, and then his ears started to ring. The archer's bow dropped, useless, onto the roof. The thin layer of stones cut his knees when he fell, both hands clasped against the throbbing, searing rune. Demon-Jace laughed with his entire body—a high-pitched cackle of glee. It ran its twinkling fingers through Jace's blond hair. "I've never possessed a parabatai before. Quite a sensation!" the spirit said low and slow and with Jace's mouth. His voice resembled bricks rolling downhill.

A wash of red. Magnus raised swirling magic to keep the demon at a distance. "Alexander—Alec! What is it?"

"I, I can—" Alec gasped, "I can feel it! The demon in Jace, I…" Alec dug all ten of his fingernails into his scalp and cried out again. "Magnus, it wants our souls!"

Demon-Jace resembled a curious scientist when he furrowed his brow and tapped a finger against his lips. "Pain. Intention. If I can push pain and intention from one parabatai to the other, what else can I do?"

"Oh, no—" Suddenly on his feet, Alec reared up onto his tiptoes like a fishhook had impaled his chin. Arms splayed, fingers twitching, he resembled a man being crucified. Alec clenched his eyes shut. When he opened them again, they were black as lead.

"Alec!" the girls cried.

"Double possession!" Demon-Jace cocked his blond head to the side, curious. "Worth writing Hell about, don't you think? Now why don't we…we try…um…" Jace's body swayed left and right, forward and backward. Blue and green eyes replaced the black. The black returned after a blink, then switched again. Jace collapsed to one knee, then the other. Blood seeped from one nostril.

Like clipped wings, Alec's arms fell to his sides. He stumbled and almost fell, but Magnus rushed over to prop him up. "Alexander?"

Alec wiped away the blood from his nose. "It can't fully control both of us at the same time," he gasped. "Takes too much of its energy, too much of—" Alec stiffened. His mouth closed, opened, and then closed again.

"Alexander?"

"Magnus!" a familiar voice called. Magnus, Clary, and Izzy all pivoted towards the sigil. Jace—the real Jace—slammed his fists against the red lights and shouted, "It's in him!"

Magnus managed only one trick before Demon-Alec punched him in the side of the head and kicked him aside where he landed, unconscious: he erased every level of protective red magic, and Jace bounded forward like an unleashed lion. One parabatai tackled the other and the pair went rolling across the roof. Clary and Isabelle sprinted to the left and right, prepared to attack with their seraph blades.

Jace briefly stunned Demon-Alec with an elbow to the eye and a punch to the kidney. He shifted his weight to pin Alec's arms and hold him down but, before he could, the demon sent itself back through the parabatai bond, and Jace punched his own mouth. Black-eyed Demon-Jace laughed at the blood on his own bruised knuckles. "Forcing two brothers to kill each other? Wow—this is the most fun I've had in a millennium!" it declared. It kicked Alec in the stomach, traded parabatai so that he could make Alec do the same to Jace, and then back switched again. "This should be part of Hell's Olympics!" said Demon-Jace. "What a workout!"

Alec spat blood. "Jace," he gasped. The elder Lightwood blocked a right cross, then skirted behind his attacker and up to his feet. "Jace if you're in there, if you can hear me…" Demon-Jace aimed a roundhouse kick at Alec's head that barely missed. "Jace, can you control it? Can you hear me? What do we do?"

"We'll scoop up a few parabatai," the demon said to itself, still preoccupied with its Olympics idea. "Each demon gets a pair to play with. We double-possess them, make them fight to the death—last parabatai standing wins! And then the possessing demon gets his head for a trophy!"

Alec rolled between Demon-Jace's legs, but didn't get his own up fast enough to wrap his ankles around the torso. "Izzy?"

"Get it to hold still and stop switching!" Isabelle shouted. "I can't—Alec, what if I stab the wrong one?"

"Stab us both!" Demon-Jace headbutted Alec when he answered his sister. The demon dove into the Lightwood again, aimed black eyes at Isabelle and, in a pathetic impersonation of Alec, said, "Save us, Izzy! You're our only hope! Ha!"

Jace somersaulted backwards and then, like a linebacker, sprinted forward and rammed into Demon-Alec's chest with all his strength. Alec's body fell back against the outer brick wall of the roof. The demon wrapped his hands around Jace's neck, but not before the Shadowhunter said, "I can hear you. I can hear you, Alec!"

Demon-Alec changed to Demon-Jace. Both Shadowhunters strangled the other's throat. The demon lowered its voice—a shift from casual playfulness to debilitating cruelty. "Jace wanted to be the guinea pig to show off in front of Clary," Demon-Jace told Alec, "not because he wanted to protect you!"

Alec struggled to inhale enough air to form a sentence.

The demon dropped the Olympics fantasies and continued its taunts. "What a smug buzzkill you are! Always so serious, so self-involved. You used to have so much fun together when you were kids! Now he'd rather spend time with Clary than you. He'd rather get kicked in the balls than hear you talk one more time about duty and honor and loyalty—blah, blah, blah! You queer, cowardly, boring son of a bitch!"

Alec felt his face burn red. More spit than syllables came out when he grunted, "Gotta stab me, Jace! Next time it's in me you have to banish—!"

The demon swung Alec around by his neck. By the time Alec rolled to a stop in front of the door, the demon had returned to him. It cracked his neck to the side and then rolled, stretched it, before cracking all ten knuckles, one by one. "You wanna know what Alec sees when he looks at you?" Demon-Alec asked Jace. "An irresponsible child desperate for attention. A disloyal brat who should be on a leash. Worse—a burden!"

Jace got up. He ducked one punch, then caught the other fist. "Alec, I can't, I'm sorry. I won't risk killing you!" Jace shoved Demon-Alec around face-first against the door. "Put an arrow through me! You hear me? Sorry to burden you, brother, but you have to!"

Demon-Alec's elbow hit Jace's sternum. "He looks down on you. You're beneath him, less than him. He's Shadowhunter royalty and you're just an orphan nobody really wanted. Alec is sick and tired of being your sidekick! Tired of you risking his life, his family, the entire Institute just to trick some random slut into bed!"

Jace grinded his teeth together. "Kill me if you have to, ALEC! Just end this!"

Demon-Alec slid a knee under one of Jace's and tripped them both. "He wishes his parents had never taken you in! His life would be so much easier, much safer if you were never born!" A horrific cackle of a laugh from deep in the demon's core. "You know what, Jace, between you and me? It's so hard to decide which one of you to keep and which to throw off the roof!" it hissed. "But I think you win—you win because your blood is different. Special. There's untapped potential in you that could really come in handy. Such rage—such frustration! So, my friend, you should say 'goodbye' to Alec now. You really should, because I'm going to make you murder him."

Jace felt the tears in his throat before they left his eyes. "ALEC—"

Alec's eyes turned brown. Jace's turned black.

Exhausted, breathless, Alec spotted and reached for an arrow he'd dropped a lifetime ago, but a black boot stamped down hard on his bare hand. Demon-Jace picked the arrow up, twirled it in his right hand, then raised it over Alec's heart. Alec began to get up from his knees—began, but stopped. He collapsed onto bare, scraped-up knees. "Sorry, Jace." He allowed his hands to lie still in his lap, allowed his blood to drip, ignored. "I won't risk killing you, either."

Jace's left forefinger slid under Alec's chin and lifted it until their eyes met. "He's screaming," Demon-Jace whispered. He tapped blond hair to indicate Jace's mind. "Screaming so loud. Such desperation! He's trying hard, so hard to stop me, to just get me to hesitate another minute, another second. My, my. This would break my heart if I had one."

Alec coughed on a mouthful of blood.

"Before you die and I enslave your parabatai forever, Lightwood, do you have any last words? Do you want to tell your brother that you love him, one last time?"

Alec's throat hurt. His everything hurt. He was barely more than a bruise. "You—like everyone else—you don't get it. You don't understand what it means to be parabatai." Alec didn't want to see those black eyes anymore, so he closed his brown ones and bowed his head in surrender. His trembling hands gestured at his submissive, martyr posture and he said, "Jace and I don't need words."

A cackling, delighted Demon-Jace twirled the arrow and plunged it down.

What Alec would've seen if he'd opened his eyes: the twirling arrow spun one last time before it collided with his chest.

It took everything Jace had. Everything he had in him to control his fingers for just that one millisecond. And in that millisecond, he rotated the arrow so that instead of piercing Alec's chest, the tip stabbed his own. Somewhere behind the scene, Clary and Isabelle screamed.

Because of momentum, because of gravity and weight and angle and the instant shock and paralysis, Jace's body kept falling forward. Alec's arrow slipped in between the first and second ribs on the right side of his chest, and the tip nicked his spine as it exited out his back. Shrieking black smoke poured out of the exit wound. Wisps shaped like fingers tried to claw at the bodies. Two seraph blades soared through the air and plunged through the smoke.

The demon disintegrated.

The roof went mute.

Jace's cheek landed on Alec's shoulder and Alec, who expected to feel cold metal instead of warm skin, opened his eyes in surprise. That pair of beautifully mismatched eyes was the best thing he'd ever seen.

The blood was the worst.

"No, no, NO." Alec wrapped his arms around Jace and shifted so that his knee supported the limp body. Jace's muscles didn't even flex, let alone make any kind of move to keep his body upright. Alec spotted blood on his parabatai's lips. "Dammit, Jace, you should've just stabbed me!" Alec's rune boiled, throbbed, cramped. A sob started to inflate in the deepest part of chest. "Hang on. I love you," Alec gulped. "I love you. Hang on, Jace, hang on."

"Didn't I hear you say that parabatai don't need words?" Jace croaked. "You're saying a lot of words…"

"I—Izzy! Clary!" Alec's voice broke—shattered. "Magnus!"

Jace flinched. "And you're saying them loudly…" Magnus, Clary, and Isabelle surrounded them. Two steles and two orbs of golden magic went to work. Jace smiled with red teeth. "Next time you're the guinea pig."

"You're insufferable," Alec sniffed.

Jace smiled. "You're adorable."

Fresh snowflakes fell. Several landed on Jace's face and Alec used his pinky to swipe them aside. White snow mixed with red blood which mixed with the colors of the desolated sigil: tree bark, mango, ruby, robin's egg, silver, ash black… The cold puddle beneath the dying parabatai turned gray…

A warm hand perched on Magnus' forehead. He jumped, instantly awake, then relaxed just as fast at the sight of his boyfriend's pale face. "Jace—is he in pain?" he croaked. "I'm coming. I'm getting up."

Alec didn't move his hand. "Even if you took everyone's strength you wouldn't have the energy for anymore healing," he whispered fondly.

Magnus frowned at the unfamiliar mattress beneath his back and the colorless ceiling beyond Alec's face. "Where—? Did I pass out?"

"We're still in the Institute infirmary. It's morning." The dark half-moons beneath Alec's soft eyes crinkled with slight amusement. "You refused to stop even when you healed Jace as much as warlock-ly possible, so I think you de-aged him by a couple years."

"He's ok?"

"He's awake. Thought you might want to know."

Magnus blinked fast to keep his tears invisible. "Alexander, I swear, if I had any doubt that spell wouldn't work I wouldn't have put Jace in dang—"

Alec, in a rare public display of affection, pressed his lips against Magnus'. The touch was soft, but the unspoken words were deafening.

Simon and Clary escorted Magnus home so that Alec could stay with his parabatai. Jace had been moved to his own room. When Alec returned, he found the shirtless, sweatpants-clad Jace in the middle of the room, hunched over a chair he was using like a walker. Alec gently pulled Jace's arm across his shoulders, walked him back to the bed, and covered his legs with blankets. Then, he went to the minifridge Jace was aiming for, and took every plate and bowl and bottle. He spread them across Jace's lap like he was a Thanksgiving table.

Jace patted the empty mattress space beside him. Alec toed off his shoes and sat with his back against the headboard.

They ate in silence.

When the pain got bad, Alec activated Jace's runes in silence.

When the memories got bad, Jace cradled Alec in silence.

And, finally, when the silence was too silent, they reminisced about the demon making Jace punch his own face, and shared the very loudest laughs.

The End