"You should have aimed for the head."
Thanos sneered, despite the massive axe brimming with power and lightning stuck in his chest, and Thor, in a flash, saw his mistake. Even the most powerful weapon the Dwarves had ever forged had not been enough to take this monster down in one strike - and now that his collection of the Infinity Stones was complete, there was not going to be a second one. The Mad Titan's words echoed back in his head.
Dread it, run from it, destiny still arrives.
Thanos raised his gloved hand; the six stones shone each of its own colour, and each with infinite shades of invisible, incomprehensible ones; his index and thumb touched.
The room was white, infinite, and definitely not real. A green skinned child stood in the centre of it (it was impossible to determine how it was the centre; but it somehow was).
"How much did it cost?" she asked, innocently.
Thanos hung his head, in guilt and shame. "You can't possibly understand." he said. "Your older self, perhaps, would."
The snap had come and gone. Thor blinked and did a double take. The universe seemed... unchanged. He still had his body and life; nothing momentuous had happened. The Infinity Gauntlet was still on Thanos' hand, but the surge of power had burned and blackened it. An acrid smell spread from it.
"Ha!" laughed the god. "You failed! Even the Dwarves' craft couldn't contain the power of the Stones."
"You fool. I won. I succeeded." said Thanos. "You merely can not see it yet."
Thor shut up, looked around for a long time. Everything looked fine. The other heroes, still stunned from the beatdown they had gotten a few seconds earlier, were slowly getting back on their feet. Captain America was already walking towards them.
"Verily, I can not." he concluded.
"That's because you're just a meathead who has never thought about the fate of the universe half as far as his hammer could reach." said the Titan, mockingly. "It took me a long time to reach my conclusion, but once I did, my resolve was unshakeable. Just look at it - this infinite cosmos, brimming with life. Growing, expanding, eating, consuming. Aiming its claws at itself whenever resources would run out, ready to kill for the right to live. Unfair. Locked into an eternal loop of joy and suffering, expansion and contraction."
Thor shrugged. "Yeah, I think that's about right."
"Ha! Right. The self-satisfaction of the lazy and the dullard. I knew I needed to go beyond. Too much life; too much hunger, in this cosmos. At first, I thought the solution would be to simply kill half of it."
"Sounds logical." commented the god. "Evil, but logical."
"But then I realised, that was only the solution an idiot would come up with."
"But also really really stupid." added Thor. "I was just getting to that."
Thanos kneeled down, ripped a flower from the lawn. He shook it, a tiny thing in his immense hand, and let the pollen flutter away, a light, almost invisible dust in the wind.
"Because, see, life multiplies itself. It is its prime objective. Before even the faintest glimmer of self-awareness shines inside it, life only strives for one thing: more life. And that does not stop. Exponential growth inevitably leads to that same end. If you don't affect its rate - if you don't change the process - then you can't prevent it, only delay it."
He let the flower fall onto the ground.
"So, I thought I could make life half as fertile. But see, that would only work for non-sentient life. For anyone else, it would barely be a minor obstacle to overcome - such is your will to reproduce. Technology can solve a lot. Where there's a will, there's a way. The will, God of Thunder. The will was key."
Thor felt uneasy. "What did you do?"
"The only thing I could do - I changed the will. It's already happening. You may be already noticing. Your thoughts, not so erratic as they were before. Recall as many images as you want - of supple thighs, ample bosoms, firm glutei - and enjoy the newfound steadiness of your heart. Lay your eyes on beautiful Natasha, who's just coming to see us, and don't feel the slightest tremble - as she questions herself for the same reason, while she lays her eyes on you..."
The God of Thunder's eyes widened in horrified realisation. "What did you do?" he screamed, as he knew the answer.
"I saved it all." said Thanos. "With a taste of omnipotence, and a snap of my fingers..."
He gestured with his hand at all the world around - the birds, the flowers, the animals, the humans, all left without something that was deep inside them, and that was now gone forever.
"...I made the universe half as horny." he concluded, with a satisfied smile.