Mian Abdullah, the man who could make people get erections just by humming. Now there's a claim to fame for you.
Mian founds the Free Islam Convocation. (Note: Even though many events in Midnight's Children are factual, this group never existed.) The FIC is dedicated to India's unity, and opposes the partition between Muslims and Hindus. Obviously they lose that fight, since India splits and Mian Abdullah ends up dead.
Those are the "facts" about him. Who is he metaphorically? Ah, that's where the good stuff is.
When we meet Mian Abdullah, India is in the middle of an optimism epidemic. Saleem describes it this way: "The optimism epidemic had been caused by one single human being, whose name, Mian Abdullah, was only used by newspapermen" (1.3.11). The whole nation was overly optimistic because of this one guy: he convinced them that India could remain unified and harmonious. Yeah, in your dreams.
Saleem says that no one calls him Mian Abdullah except for journalists. What do they call him? "To everyone else, he was the Hummingbird, a creature which would be impossible if it did not exist" (1.3.11). Did you know that hummingbirds are crazy weird, and scientists had no idea how they migrated across continents or flew backwards for a long time? It probably seemed miraculous. In other words, Mian Abdullah, the Hummingbird, is a miracle that can save India from partitioning.
The miracle doesn't last for long. Abdullah dies in a bloody assassination that becomes the stuff of legend. And…the optimism epidemic is over. Saleem says,"Mian Abdullah was a false start for a lot of optimistic people; his assistant (whose name could not be spoken in my father's house) was my mother's wrong turning. But those were the years of the drought; many crops planted at that time ended up by coming to nothing" (1.5.63). Guess it's a pessimism epidemic now?
Abdullah and his death set the tone for every other time that people are optimistic in the novel. We know how it's going to end already and it's not going to be pretty. Amina and Ahmed's love affair ends with Amina's craziness and Ahmed's stroke; Padma's long-awaited marriage ends in the death of her new husband; in other words, Mian Abdullah teaches us that there just is no such thing as a happy ending.