He was dying. Stiles knew this with every fiber of his being. He had gone too far this time with his magic. The spell had been a powerful one – one that Deaton had warned him not to attempt yet – and it had been too much for Stiles to handle. Instead of merely wiping out the opposing pack it had also recoiled on him and now he could feel the fire inside his body as it unmistakably burned away his life.

He slammed his eyes shut as another wave of pain wracked his body. After everything – all the werewolves, gnomes, pixies, vampires, and even a freaking yeti – the thing that ultimately killed him was himself. His own arrogance in thinking he could do a spell that was years too advanced for him.

The agony sweeping through him quite suddenly started to fade and his eyes flew open. Derek was on his knees beside Stiles, his hand gripping Stiles' hand tightly as his veins turned a sickly black. Glowing blue flickered across Derek's eyes as he gasped in pain but he didn't let go. Of course he didn't. Stiles was his mate. They had been together for years now and Stiles was well acquainted with the feel of Derek leeching his pain away.

Stiles weakly tried to shove Derek off but his body wouldn't respond properly to him, "Derek, stop." He whispered, unable to find the energy to speak louder. It didn't matter; he knew Derek could hear him. "Derek, I'm dying. Taking my pain won't save me. It won't do anything but hurt you." Every time Derek took his pain Stiles hated it. He hated seeing Derek hurting because of pain that wasn't his.

Derek was still reeling from the shock of how much pain Stiles was giving off but he managed to say through gritted teeth, "I can make it easier for you." He was shaking with the effort it took not to crush Stiles' hand in his as the burning sensation flowed through him. He knew now what his family had felt in their final moments as the building around them burned. The only difference was that the fire was inside his body and he couldn't put it out. Every nerve was firing signals to his brain telling him to let go; telling him to stop taking on this pain. He fought down the instinct and held on with everything he had.

"You'll just end up killing yourself." Stiles spat out in frustration. He feebly clawed at Derek's hand trying to get it to let go. It didn't matter where the pain went; the magic was still destroying Stiles' body. His eyes met Derek's and he pleaded with him again, "Let go! We'll both be dead and you'll have died for nothing."

"Good!" Derek roared. "You know damn well I don't want to live without you. Do you have any idea what it's like for a werewolf to lose their mate? I'd rather die."

Derek had seen what happened to a wolf that lost their mate. So had Stiles in fact. Peter was what happened. Peter had watched his mate burn to death in the basement of the Hale House and he had never recovered. All the kindness and love that Peter Hale had once possessed was replaced with insanity and rage. Rage that made him slaughter his own niece for her power, made him manipulate a young girl into bringing him back from the dead, and made him do his best to tear apart the remnants of the Hale pack.

A wolf went insane when their mate died.

So Derek held on to Stiles. He ignored the protests that, grew weaker and weaker, telling him to stop. He ignored the tears streaming down Stiles' face as he desperately tried to pry Derek's grip from him. He ignored the inferno that burned through him as it left Stiles. Instead he focused on the man dying in front of him and he felt his own face wet with tears. This man who had come into his life so unexpectedly and slowly wormed his way into Derek's heart was going to die. Stiles was dying.

Derek felt his strength waning and he dully noted the blackness seeping into his vision at the edges. Moments later he found he couldn't hold himself up and his body collapsed on top of Stiles.

Stiles' desperation spiked and his voice trembled with fear as he felt the crushing weight of Derek on top of him. He couldn't move and even if had been able to he knew that he didn't have the strength to get Derek off him, let alone get him to stop. Breathing was getting harder now but Stiles couldn't be sure if it was because of Derek or simply because of the looming death.

Stiles had a quick moment to notice that the black veins had stopped, then to notice that Derek's chest had stopped moving, and suddenly the dull ache that had been fluttering around in Stiles' body turned back into the agonizing pain he had started with. The pain in his body was minor compared to the knowledge that Derek was gone. The last few minutes before his own life slipped away were spent apologizing, to any god who would listen, for killing Derek Hale. Then everything faded to a cool welcoming darkness and he took a last shuddering breath before his body stilled forever.