An uneasy peace holds between Ruslan and Rustam Shapiyev in the Daghestani village of Komsomolskoye.
Younger brother Rustam, who has taken the name Abubakar, says he loves and respects his older brother, who has adopted the name Magomed.
"Of course, a brother is a brother. We are obligated to maintain kinship ties," Abubakar says. "Magomed is my older brother. When he enters the room, I stand. I serve him food. I respect him and seek his advice. We help one another."
But when it comes to religion, things are not so harmonious.
"When he tells me, for instance, that I shouldn't celebrate the Prophet's birthday, I answer: 'Stop. This is where this conversation must end,'" Abubakar says.
Threat Of Detention
Twenty-eight-year-old Abubakar is a Sufi Muslim, a branch of Islam that is officially recognized in Daghestan. Magomed, 31, is a devotee of Salafism, a confession that is banned under the republic's 1999 law on Wahhabism and other perceived forms of extremism. Four of the brothers' cousins have also adopted Salafism.
In this volatile republic, Magomed, who declined to be photographed for this article, might easily be whisked off the streets by police at any moment and held without explanation.
In fact, Magomed says, it happens frequently.
"I am not going to kill my brother, but [the authorities] are coming to kill me," he says. "If I even try to go out in public and speak about my desire to live in a Shari'a-based state, I would disappear. I've been taken to the police station many times. Many of my friends have disappeared.
"I remember one morning when I was on my way to prayers," he continues, "a police van stopped next to me and they shoved me in without any explanation. At the police station, they asked me why I was running away from them. I answered: 'I didn't run anywhere. I was walking to morning prayers at the mosque.' They threatened me, tried to scare me."
He claims that two of his friends are serving time in prison after confessing under torture to crimes they say they didn't commit.
Independent human rights organizations estimate some 800 men in Daghestan between the ages of 18 and 40 have been killed so far this year in the insurgency, official reprisals, and sectarian violence. About 600 of them were ethnic Avars, like the Shapiyev brothers.
Said-Afandi Artsayev, a spiritual leader of Dagestan's Sufi Muslims, was killed in a suicide bombing in August.
Abubakar is also uneasy about the violence.
"When he was interior minister [of Russia], Rashid Nurgaliyev assembled at a local club here the widows of all the slain police officers. A whole army of women in mourning dress showed up," he says. "They were all young and beautiful. What is going to happen to them now? Soon, we will have no one to take care of our elders."
According to Abubakar, Magomed turned to Salafism while he was living in the Russian city of Veliky Novgorod and running a small business in 2009-11. Abubakar says his brother was influenced at that time by "extremist websites."
Magomed, however, insists that Salafism is distinct from Wahhabism and that the authorities are using official media to create a false impression of Salafism as violent and extreme.
The brothers say they are working hard to stay close, for the sake of their 51-year-old mother. Magomed says he tries to avoid theoretical conversations with his mother and focuses instead on aspects that the two strands of Islam have in common.
Abubakar adds that the Sufi elders he has consulted have also advised him not to reject his brother. He takes his religion seriously -- and his family ties to his brother, as well. But he tries to focus on the bigger picture.
"What are we supposed to do now? Kill each other? Am I supposed to kill my brother and my four cousins? Is that really our fate?" Abubakar asks. "I'm more concerned about how pure I will be when I stand before Allah. All the other stuff is one thing, but that is something else. Why do I need all of this?"
RFE/RL correspondent Robert Coalson contributed to this report