LUCKNOW, India - The tale of their feud begins in the 18th century, with an ancestor who served a Mughal emperor and led an aristocratic family to wealth and power.
It has reached the point now with the two - white-haired brothers-in-law, living in adjoining apartments in a palace that is past the point of crumbling - both claiming the throne of a kingdom that hasn't existed for 150 years.
"I think he's obsessed," said Ibrahim Ali Khan, a former oil company executive and the leading claimant to the title in question: Nawab of Awadh. "Once you realize you are not the nawab, and the whole town knows that you are not, even then you want it. What would you call it? You'd call it an obsession."
His brother-in-law calls it something else.
"There is this thing known as megalomania," said Jaffar Mir Abdullah, the more recent aspirant to the long-gone throne. He's a former medical equipment salesman whose sister is married to Khan.
Their 15-year feud, in a city once famed for its gentility, has become a matter for public gossip and a reflection of India's ambivalent relationship with its bewildering array of aristocrats.
Because if aristocrats don't matter at all in modern India, they also matter very much.
"Royalty is a very complex thing in this country," said Malvika Singh, a magazine publisher who often writes about politics and culture. "What is modern? What is feudal? I think India is a mixture of all of these."
Officially, the assorted nobles - nawabs, nizams, begums, maharajas, maharanis, sultans, and others - don't amount to anything.
India's aristocratic families were stripped of political power at independence, in 1947, and their feudal landholdings five years later. The final blows came in the 1970s, when they lost their government allowances and legal right to their titles.
"We had some very tough times," said Khan, a 63-year-old with sad, deep-set eyes, pouring whiskey as he told the story of Awadh.
From memory, he lists the many rulers of the kingdom, which stretched across India's north. He turns nostalgic as he talks of Lucknow, its last capital, and how it was famed for arts and poetry.
The kingdom disappeared when it was annexed by Britain in the 1850s, but the descendants of the ruler - the nawab - remained in the city as powerful landlords.
Today, India is fiercely proud of being the world's largest democracy, with a fast-growing economy. The new elite celebrates entrepreneurs and technocrats - and relegates royals to entertaining wealthy foreign tourists in palaces-turned-hotels.
In Lucknow, there are two angry brothers-in-law.
Conversations with both tend to start in the early 1700s, when Awadh's first nawab was an aide to the Mughal emperor. There are digressions into family trees of mind-bending complexity.
There are tales of the Sheesh Mahal - the Palace of Mirrors - the crumbling, once-ornate 18th-century mansion that envelops a century-old addition where the two live, Abdullah in moldy, high-ceilinged rooms and Khan 30 feet away in a freshly painted apartment.
In separate interviews - once close friends, the two men seldom speak these days - Abdullah lashed out at Khan for everything from his mental state to his real estate decisions. Khan ridiculed Abdullah for his claim to be among Awadh's nobility.
"His grandfather married a second cousin of my father in 1917. The family had never seen the face of Lucknow before then," said Khan. "Then, in 1995, he starts calling himself a nawab!"
That is when the trouble began.
In the 1990s, Abdullah began working with travel agencies that offered tourists a chance to dine with nobility.
A friendly, potbellied man, Abdullah is a natural storyteller who enjoyed introducing tourists to Lucknow's history. His brother-in-law, he said, is being pedantic about old aristocratic legalities.
"Nawab is not even a title now," he said, arguing that many men in the family can use the title. "This is the family of the nawabs. Not one nawab."
Unless, of course, you've been raised to believe you are that one nawab.
"Being the eldest son, I got the title," Khan said angrily. "If it was the old days, he would not have dared to call himself a nawab!"