The butterfly landed on his fingers awkwardly, he could see its wings slowly disintergrating, it was dying. Its life would soon end like all life inevitably did. He bent down and gently placed the buterfly on the ground, the thick grey ash would we where it would die. Going back to whence it came, ashes to ashes, dust to dust.
He straighened up and checked his blck designer suit, he dusted a speck from the Maverick jacket and began walking down the ruined street. The buildings were already crumbling. The sonic blasts early had broken their foundations and the radiation had weakened the metal supports. The thick grey ash was still falling, covering the landscape like snow would have on a cold winters evening. Technically it was a winter, but not one nature intended. The Nuclear Winter was coming. The end of the human race.
He sighed and looked around, it was amazing how a civilisation could destroy itself so quickly. He could still hear the nuclear warheads going off in the distance.
"We all go hell." he said quietly, "The humans purge themselves from the world and destroy it in the process."
He passed a dead body, an old man, his time had come earlier than he'd expected.
He froze, he could hear something, something alive in the wasteland, someone crying for help. Begging for someone, anyone to come.
The figure nodded slowly and rose into the air, he floated towards the sound, slowly at first but faster and faster as the pleas became more desperate.

He landed in an alleyway, the please had died to soft sobbing. He stepped through the ash, it clouded around his black boots as he approached a dumpster. The sobbing was getting fainter, the person was dying. He stepped around the bin and looked down, he froze, it was completely unexpected.
There was  girl lying there, she was the same age he'd been when he'd been brought over. He eyes shifted lazily to him, the radiation was starting to take serious effect on her.
He crouched beside her and held her head under one arm, even through the ash he could smell her hair, it had been freshly shamppoed. her face was pale and clear, her eyes green like grass, the same colour as his, she was curled intoa  slight ball, her blue jeans and t-shirt were covered in ash.
"Save me." she whispered, eyes losing their focus.
"Yes." the figure nodded, he closed her eyes with his hands and her breathing began to die. He opened his mouth, canine teeth extending to their full length, her tilted her head to one side and bit into it. The blood was so sweet, so young and full of life. Life that was being drained away by radiation and sadness. She'd already lost her parents. Would this help her? He sat back, it was too late now, it was done. The bite marks on her neck began to heal. Finally her eyes opened and blinked in a daze.
"You saved me." she said quietly.
The figure placed a finger across her lips, "Save your strength, you will need it later."
With that he picked her up in his arms and stepped back onto the street. He looked around at the ruined buildings for a moment before adjusting the girl in his arms so her face rested on his shoulder and legs hung over his other arm. Her hands moved to her lap and her head wriggled closer to his neck.
She whispered two words before slipping into quiet sleep, "Thank you."
The figure shook his head, do not thank me yet, you don't know what you have become.
He continued down the street, the duo the lone survivors at the end of the world.