I don't own the Avengers or other Marvel (MCU) films or characters. I do own this plot and random original (side) characters.
Some story's background:
In my story, Hades may have kidnapped Persephone, but didn't rape her, treated her with respect. During the first three months, Hades noticed her selfishness and had fallen out of love with her. When three months had past, Hades returned her to the surface world.
Some of Hades' powers are taken from a story "Demeter's wish". For example, that he can fly using his shadow magic.
At the time, my story takes place, Avengers are newly formed and there are plenty of friction between them, especially, between Natasha Romanova and Bruce Banner, between Tony Stark and Steve Rogers and between Tony Stark and Natasha Romanova. There might be some bashing of Steve Rogers (I don't like him) and Natasha Romanova (I don't like her actions in regards of Tony Stark).
Gods' function in the world is to decide and control natural laws and help their people to protect themselves. Although, my story operates on the idea of most gods being real (Egyptian, Greek, Indian, some Asian gods), in my story will mainly feature the Greek ones.
Most gods also have their own residence. Hades, Hecate, Thanatos have theirs in the Underworld, while some others have theirs either on the Earth or in the Heavens.
In the New York fought Ares, Hades, Artemis, Apollo and Athena.
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As the portal opened above New York, several deities had a short meetup in the Area's Hall. Together there gathered war gods, hunt gods and a death god - Ares, Athena, Apollo, Artemis and Hades. Long ago, they had been nominated to deal with any attackers of Earth as their powers were most suited to war and battle than any other god's. They felt the alien invaders and met to discuss what should be their response.
Ares and Hades advocated taking immediate action against the attackers and letting mortals to learn of their existence. The twins, Apollo and Artemis, voted to only slightly help the mortals from the shadows keeping themselves secret, leaving people to deal with aliens themselves. Athena hesitated. The best scenario would have been to deal with aliens themselves without any human knowledge, but these aliens had already outed their own existence by attacking a highly populated city. She thought about pluses and minuses of such actions and decided to vote for immediate action.
Athena hefted her spear and let out a war cry. "To the battle for the Earth!" She stepped into her chariot. Ares did the same. Both Artemis and Apollo grabbed their bows. While Apollo climbed into his chariot, Artemis hopped on her horse.
At the same time Hades shadow travelled to his Armory, where he had his armor and weapons. He chose a long scythe, which channelled his powers excellently, and put on his oldest armor, used in the Titan war. He, then, hesitated about his choice of transport. After a few seconds of back and forth, he said to hell with it and decided to fight flying on wings, which he promptly formed with his magic. Hades flew through his self-made portal to the New York.
The gods started to fight the aliens. From above the city Apollo released an arrow after an arrow. Artemis flew all around, while letting her arrows fly. Athena and Ares flew to and between aliens, while killing them with spears. Hades with his scythe could release his death power in wide waves, killing aliens by droves or just slicing them or their flying crafts.
In the New York, the portal was just fully opened and the aliens were already flying through. Tony Stark rose up in his Iron Man suit and saw something unexpected. There were a few people fighting against the aliens in a strange way. A darkly clad man with wings! waved a scythe and aliens in the indicated area fell dead. A light-haired man used a bow while flying in an ancient looking chariot, another person did the same only flying on a horse, which flew without any help! Last two people were looking quite blood-thirsty, while slaying aliens with their weapons. It blew Tony's mind to see them flying without any obvious technology. Tony wasn't sure about them or their origin, but seeing them fighting aliens cast those strange people in his mind as allies. Tony shaked his head, looked back at Loki, standing at his window, and flew to the battle.
"Cap, there are some people already fighting the Chitauri, I assume they are our allies." He said in the comms.
"What are you talking about… What!" Rogers spoke at first annoyed, and then, disturbed. The moment, when he noticed them, was starkly obvious.
"They are, who I was talking about."
"You don't need to show off, we all can see them, your ego is big enough." Snidely, said the Black Widow. Tony just rolled his eyes at her attempt to put him down. He knew that Romanova hadn't managed to see through his masks and was lashing out at him out of wounded pride.
When remaining Avengers arrived, Tony Stark said "Call it, Cap." Avengers hadn't expected that Stark would allow him to command the battle so easily, but went with it.
Hades truly enjoyed this battle. It was rare for him to have business in the surface world so each occasion, where he had some business with other gods, was joyful. During the battle Hades mentally reviewed what they should tell to humans and what to avoid mentioning. He sent a message to Hecate to grab some freshly dead lawyers and write up a contract for future cooperation of the Greek gods and the UN.