Magnus is laughing at them.
In the past, the sound of his laugh was—in Alec's perfectly unbiased opinion—the most wonderful sound in the world. Now, it is horrifying. It's low and cruel and Alec can do nothing but stare as Magnus rises to his feet.
"Bravo," Magnus says, golden irises flashing even in the weak light of the courtyard, his gaze resting immediately and singularly on Alec. "You were ready for me."
"I was ready to talk," says Alec, swallows hard as he forces his voice to come hard and firm. He has to be a leader now. "I was ready to find out if there's anything of you left… I need to be sure."
The way Magnus tilts his head is almost grotesque, angling too far like he's trying to break his own neck. Alec forces himself not to look away. "You're desperate or you're oblivious. Either way, you're a fool. The warlock who left you in Alicante… I'm not him anymore. I'm better now."
"You're not. You're sick."
Again, Magnus just laughs. Alec fights back a wince, forcing himself to continue.
"Look around you, Magnus. We were forced to trap you like a beast. The old you—the real you—would never make me do this. You know how to control your power and you know what happens when you don't. You told me about what happened to your step-father."
"Yes," Magnus says, unapologetic. "He was cruel and abusive. He hurt me, so I burned him alive. I did the same to my father. They both deserved it." His eyes lift to Alec's own, gleaming gold. "When I break from your pathetic excuse for a cage, I will do the same to you and your friends."
Alec shakes his head. "You won't."
Magnus hums absent interest, wandering around the inside of the square, running a careful finger across the invisible barricade, making it spark and crack, burning his skin red and black. His expression doesn't falter and the lack of emotion is the worst. It's awful to watch him so deranged.
"Stop it," Alec orders, still despaired to see him hurting even when it doesn't show on the warlock's face.
"Why?" Magnus says, his eyes calm and without a hint of pain as he lifts them to Alec. "Does it affect your delicate sensibilities to see me powerful?" He presses a palm to the cage, letting his skin sear as he leans close to drop his voice low. "Are you afraid of me, Alexander?"
"I'm afraid for you," counters Alec.
"Alec," Jace says, pulls at his arm to tug him in back, angled away from Magnus. "We have to do it, now. He can't be talked down. It's demon ichor inside him. It has to be purged away."
"Conspiring doesn't work if you're within earshot, boys," Magnus drawls, smirking when the brothers look to him warily. "How exactly do you plan to purge me? You're mortal and this cage of yours… well, it won't hold me for long. I'll break free soon enough."
"It doesn't have to be for long," says Jace. "It just has to be long enough… Izzy?"
Golden eyes turn to search over Alec's shoulder and they narrow slightly. Alec reluctantly follows his gaze, watches his sister approach. Glorious catches the light strangely in her wielded grasp. When Alec turns back to his boyfriend, concern grips his heart to see the warlock on the cusp of a smile.
"Well now," says Magnus, looks to him. "I didn't think you had it in you."
"We're going to save you, Magnus," Alec promises, hoping his voice comes more confident than he feels.
The warlock just laughs, tipping his head back as the sound overcomes him. "You think this will save me?" he queries, shakes his head. "Oh, Alexander… Oh, you poor boy…"
He reaches out and Alec winces in preparation for him to be burned. It never comes. Magnus's hand passes straight through the barrier, light fingertips upon Alec's cheek. The shadowhunter gasps softly, fights to step back. Magic wraps around him, binds him in place, frozen.
"Alec!" Jace yells and Magnus casts a careless hand to him, striking magic against his chest and flinging him backwards. He does the same to the others. Clary and Isabelle grunt and hit the floor somewhere behind him.
"No," Alec whispers, unable to turn his head or to speak any louder. "Magnus…"
The warlock smiles, steps from the cage, its walls meaning nothing to him now. "Alec," he utters, stroking his fingers across the shadowhunter's cheek. "If you think the sword will save me… someone has misled you."
"It'll purge the demonic power from your blood," says Alec, fighting back the tremor from his voice.
"That is all my power," Magnus replies calmly. "It is my life-force. If you use your angelic sword on me, I die."
"How do we know you're not lying?" Jace snaps, struggling to his feet.
Magnus casts another absent blast of magic to knock him down. "Alec," he says, his hand pressing to Alec's cheek, his skin healed now, unburned. "It seems you are prepared to kill me."
Alec shakes his head, a denial ready on his lips.
He never gets a chance to voice it.
Magnus slams him back with a jolt of magic and a cry of pain breaks Alec's lips, something cracking too loud in his chest. He knows broken ribs when he feels them, although he never imagined Magnus would ever be the one to inflict such pain upon him. A gasp of anguish tears his throat as he tries to push himself upright.
"Magnus," he whispers, lifting his eyes to the warlock as flame-like magic dances upon his fingers. "Magnus, please don't."
"You claim to love me and now I discover you would rather see me dead than see me as I am," says Magnus, twists the magic a little so it cracks like lightning, like a tiny storm in his hand. "Make up your mind, Alexander. You cannot love me and also wish me dead."
"I do love you," Alec says, stiffens and grunts in pain as Magnus's magic whips out to wrap his throat. "Magnus…"
"Do not lie to me," warns Magnus, his voice low and terrible.
Alec shakes his head. "Not a lie," he insists, chokes and fights for breath as the magic tightens painfully. "Magnus, don't—"
There are footsteps behind him and Magnus tosses him absently to the floor, turns to meet Jace with Glorious, a jolt of magic casting the sword from his hand. A silver whips slashes to his arm, coils tight around him, but Magnus just tugs it closer, forces Isabelle to stumble and release her weapon.
The blade of Glorious catches wickedly in the artificial light seeping through the institute's stained-glass windows and into the courtyard. It is blinding to Alec's tear-glossed eyes.
He takes one look at Magnus, casting a dark and newfound power to people who used to be his friends, and scrambles to his feet, running to the sword. Grasping Glorious with both hands, Alec tries to ignore how abnormally heavy it is, how it resists him as if it knows what this will do.
Magnus turns on him just as he lunges forward and the blade hits with a sickening crack into Magnus's shoulder. Obsidian shards explode outwards from the tip of the blade. The blackness drains from it as it breaks away, leaving clear crystal fragments raining to the ground.
Magnus screams. Alec wishes he were deaf at this moment, wishes he could block out the warlock's pain. He wrenches the blade from Magnus's shoulder, discarding it to the floor in favour of catching Magnus before he can hit the ground. His body is limp and cold in the shadowhunter's arms. It's as though all the life drains from him as the darkness flees the obsidian.
The warlock is paling by the second. The darkness fades from his eyes, the demonic power draining from him. The obsidian comes crumbling like a landslide from the tear in his shirt. He's bleeding now. Crimson gushes thick and fast from the gash left in the wake of the dissolving obsidian.
Magnus breathes slow, shallow. His chest isn't moving nearly enough. The golden eyes come to Alec's face, settling there with a distinct lack of focus. Still, his hand lifts, his fingertips running light over Alec's cheek.
"Alexander…" he whispers, something light and fond and so painfully familiar coming back to his eyes. "Thank you…"
Alec shakes his head, grabbing Magnus's hand when it slips along with his eyelids. "Magnus," he coaxes, squeezes his hand anxiously, but to no avail.
Magnus is unconscious. Blood stains cracks of translucent obsidian welded into his shoulder, but the crystal is shattering and falling away and beneath it is a fresh torrent of blood.
"Magnus…" Alec whispers again, closes his eyes when he receives no answer.
"Alec," a voice says and he looks up to see Clary. "We have to get him to the medic bay."
Nodding stiffly, Alec gathers Magnus up against his chest, fighting to ignore how limp and unresponsive his body is in his arms. The threat of Edom is gone. Another fight is beginning now; the fight for the warlock's life. Alec refuses to let Magnus lose this one.