(Comprehensive British and American) What If There Was an Extra Decadent Uncle in the Avengers?

Alvin Williams, an uncle who is nicknamed an old man by kids on the street. Innocently, he touched his hair that had not been cut for a long time: Actually, he is only thirty years old. Does he become an old man at the age of thirty? Ivan is a doctor, and he doesn't have any lofty ideals. He just wants to open a clinic in the small town where he lives now, and then work for decades, and then retire and enter his coffin. He has never thought about leaving here. Until one day, a staff member who called himself the Strategic Homeland Defense Attack and Logistics Bureau came to him and invited him to save the world. Ivan looked at the agent in a neat suit in front of him, took off the cigarette from his mouth, and felt complicated for a moment. The preliminary CP is determined to be Team USA~ In general, this is a reunion of a man who smokes constantly and drinks with everyone. His decadence is not shocking to the world, it can only be said to be slightly decadent. Also, the protagonist's ability can be considered a bug. This is my first time trying this kind of protagonist. Please forgive me if the writing is not good. Also, the author has not had much contact with medicine. Please forgive me if there are any bugs. I bow—— Intention: The feeling of losing direction and slowly regaining it