WARNING FOR MAJOR CHARACTER DEATH AND UNHAPPY ENDING. I'm so sorry. This genuinely hurt to write.
Sebastian's heart stops, and his blood runs cold because, this cannot be fucking happening right now.
Nightbird cannot be Blaine. Blaine cannot be Nightbird. Blaine is safe and sound at his apartment, curled up on the couch, catching up on one of his dorky reality shows that Sebastian constantly teases him for - not bleeding to death right in front of him in an abandoned warehouse after a brutal showdown with one of Ra's Al-Ghul's nameless lackeys, who lies sprawled out on the floor beside them, lifeless after Sebastian ran him into the wall full-force.
But, no. There's no mistaking him, now that he's out of the shadows – now that Sebastian can see him up close. There's no mistaking those eyes. Hazel orbs gaze back at him through long eyelashes, pupils shrinking by the second. The hair over his forehead is starting to break free from the gel, curling in on itself from the sweat that they've accumulated from battle, and Sebastian pushes it back, ignoring the whimper that escapes his throat.
How could he not have known? It was so obvious. The random disappearances, the cancelled dates, the fact that he felt himself draw closer and closer to Nightbird, despite his feelings for Blaine.
Or maybe, deep down inside, he did know. Maybe he chose to ignore it by lying to himself, allowing himself to believe that Blaine was not mixed up in all of this.
Blaine lets out a harsh cough, eyes shimmering, body contorting as he writhes in agony, and his face twists into an expression of immense discomfort.
"Blaine," Sebastian whines, gripping onto his arms. "Blaine, please- you can't-"
"Sebastian," Blaine croaks, and it's taking up every ounce of his energy – Sebastian can see how he's struggling for movement, fighting for breath.
He could get him to a hospital within a matter of minutes, but he knows that it won't do any good – it would be senseless. He doesn't have long left, and Sebastian owes it to Blaine to stay by his side.
Blaine reaches up to cup his face with quivering hands, and a sob escapes Sebastian. He's barely aware of the dampness around his eyes, though, because all he knows is that Blaine is dying. He's dying, and there's nothing that Sebastian can do about it.
"Sebastian," He repeats, gazing up at him with reverence. "You're him- you're- you-"
"Shhh," Sebastian soothes shakily, scooping Blaine up carefully, rearranging him so that he's cradled in Sebastian's arms. "I'm here, Blaine. It's okay. It's all going to be okay."
He tries to ignore the throbbing lump in his throat, and the fact that it feels like his ribs are being crushed from the inside. If these are going to be his final moments with Blaine, he needs to hold himself together long enough to say goodbye.
And fuck, he's not ready for this - he'll never be ready for this. He holds onto Blaine a little tighter, rocking him back and forth. He's not sure who he's trying to comfort, here - Blaine, or himself, but it doesn't seem to be helping either way.
Shallow breaths fall from Blaine's lips, and Sebastian presses his forehead to Blaine's, closing his eyes, and he sounds out a soft whimper against his will.
"I don't- want- to go-" Blaine chokes out between gasps, and Sebastian feels his heart shatter all over again.
"It's going to be okay," Sebastian repeats, breath catching the back of his throat. The lie leaves a bitter taste on his tongue.
"I love you, Seb." Blaine tells him, as though he's said it a million times before. He hasn't though - this is the first and last time that Sebastian will ever hear those words fall from Blaine's lips.
"I love you too, Killer," Sebastian replies, tightness in his throat straining his voice. "Forever and always."
He brings their lips together, in one last desperate attempt for contact. They've done this before – on numerous occasions, but it's never been so filled with longing and despair. Their mouths move together with urgency, Sebastian clinging onto Blaine as tightly as he can.
Just like that, Blaine wilts in his arms, eyes glazing over, and Sebastian's world falls apart in an instant.
He stands in a temple in Nanda Parbat, facing the man that he deemed to be responsible.
"I need you to understand – when he rises, he will not be the same."
"You did this," Sebastian snarls, staring the man down in blind fury. "Bring him back. I know that you have the power."
Ra's shakes his head slowly, a solemn look on his face, as if he regrets the entire ordeal. All for show, Sebastian knows. This was his plan all along. Somehow, he knew their secret identities. Somehow, he knew what Sebastian felt for Blaine. It's the only explanation.
"I do have the power. But I also have conditions."
Of course he does, Sebastian thinks to himself, silently ripping the guy limb-from-limb in his own mind. He can't, though. It would be suicide – not to mention, Blaine would still be gone.
He needs to co-operate for Blaine. He has no choice in the matter.
It's three years later when Sebastian finds himself back in Westerville on a mission for the League of Assassins. Gone is his red suit, and in its place, a full-body suit of black, completely covering every area of skin, including his face.
The last time he saw Blaine, he was rising from the Lazarus Pit, gasping for breath. Sebastian hadn't been allowed to say goodbye. Already covered in black, Blaine hadn't realised that Sebastian was in attendance, watching his revival with a tightness in his chest – a tightness that hasn't left him since.
Sebastian still loves him with every inch of his tattered soul. It's been three years without contact – Blaine thinks that Sebastian is dead, and for all intents and purposes, he's come to accept it. It's better this way, he tells himself. But Sebastian will never move on.
Nightbird moves swiftly in the shadows, taking league members down one by one, and Sebastian's chest swells with pride. He hasn't moved in on them yet – can't bring himself to fight Blaine, no matter what Ra's has demanded of him. His one condition was that he wouldn't harm Blaine, and Sebastian will make sure that he oversees that with what little humanity he has left.
It happens in an instant – one moment, one of the assassins moves to attack Blaine with a blade, and Blaine's back is turned. In seconds, Sebastian moves in in a burst of light, pushes the attacker out the way, and grabs Blaine, throwing him over his shoulder and speeding as fast and far as he can.
They stop in the middle of a wheat field somewhere north of Indiana, and he gently lowers Blaine to the ground, who stares back at him wide-eyed.
"Sebastian?" Blaine breathes, reaching out to the material covering his face.
Sebastian takes a step back so that Blaine's hands close in on thin air. "Don't," he warns.
Blaine flinches, but doesn't avert his eyes. He's watching him like he's the god damned messiah, which couldn't be further from the truth.
He can't do this. He's fucked – he's so fucked. Blaine knows he's alive now, and he won't give in until he has Sebastian back. Sebastian is gone, though. In his place stands a ruthless killer, hanging on to his last shred of humanity for dear life.
He forces his walls up, hardens his shell, and gathers what little resolve he has left. "Don't look for me."
Blaine reaches for him again, but Sebastian's gone in a flash.
Ra's finds out that Blaine is looking for him shortly after, and gives Sebastian a choice – either he dies, or Blaine does. He doesn't even need to think about it, and allows himself to be led to the gallows without struggle.
He regrets nothing. Everything he did, he did it for Blaine. He can die in contentment, knowing that the person who was once the light in his life is safe. He closes his eyes as the rope is being tied around his neck, and takes a deep breath.
For Blaine.