The good news: he transmigrated into the Marvel universe. The bad news: he was pretty useless at first, and the worldbuilding seemed rather muddled.
So he did something pretty shameless: he pretended to be a sage.
Tony has palladium poisoning? He befriends him early and casually suggests a new element. Hulk goes on a rampage? He sticks on a calming talisman, and Hulk turns into a good little boy on the spot. During the Battle of New York, he sits on a rooftop selling talismans and makes a fortune off the war.
Then the Ancient One realizes he doesn't belong in this universe and lays down three prohibitions. He agrees to them in public, then heads straight to an antique shop in San Francisco to learn chi magic from Uncle. His neighbor, Mrs. Chen, brings him soup every day, and after being introduced to the symbiote world, she gains a partner of her own.
Later, an ancient demon awakens in San Francisco, and the twelve talismans are scattered across the globe. He simply gets both sides to help each other out: the Avengers fly to San Francisco to fight the demon, while the Dragon Team comes to New York to deal with the Shadowkhan. Tony sends Uncle monitoring equipment, and Uncle makes Tony soup.
Thanos raises his gloved hand, and a yellow talisman is slapped onto his forehead.
"Safe travels."
No one can die. Not a single person.
