It was a warm summer's evening when the two immortals came together. One walking around in the sunlight, like he would never see it again. The other with cat eyes smiling at a blue skinned man buying ice cream, humming an old lullaby.
They didn't think they'd last this long, they thought they'd die in the war, or the fires of hell when there was no one else to save them. But they survived. The others, Clary, Jace, Isabelle, and Alec had children, and had fought more monsters and demons then most shadowhunters would in a lifetime. Their lives always hanging on by a thread - as if they would have it any other way - and one by one that thread was cut.
Isabelle was the first to go. She died in battle, weapon in hand. The way she would've wanted. Simon was devastated, but he got through it, faking a smile until it became real.
Clary went next, outnumbered by Ravener demons. She fought hard, killing almost all of them until she bled out. Jace found her. Simon thought that man could never cry but there he was, tears streaking down his face as he carried her body up to the New York institute.
Jace went off the grid, hunting down all the demons he could find. They talked now and then, but he seemed distant. Alec went to visit him when Jace would allow it. That wasn't very often. Their last mission together Jace took on more than he could handle, swarmed by Ravener demons. Ironic that he went the same way as Clary. Alec wore white for years, the parabatai rune faded grey.
Alec grew old, watching his children grow up. He died surrounded by his husband and children, his nephews and nieces. His last heartbeat in sync with his husband's, holding his hand.
The immortals sat on a bench overlooking the lake in the middle of the park. A comfortable silence between them as the vampire drums his fingers against his leg, the warlocks eyes glinting in the sunlight. The old friends lost in thought, the world moving around the still figures. Watching the sunset paint the sky a multitude of vibrant colours. Remembering the times of fighting in the Mortal War. Remembering all the good times with loved ones.