Fratricide was the name of the game in Fear the Walking Dead's episode "Brother's Keeper." Neither of the Otto brothers directly killed the other, but Troy's (Daniel Sharman) ill-considered act of violence led to the death of Jake (Sam Underwood) after Jake pointed a gun at Troy's head. In fact, Nick (Frank Dillane) stopping Jake by knocking him down a hill led even more directly to Jake's death than what Troy did, as did his removal of Jake's bitten arm. So now Nick's going to carry another death on what's left of his conscience.
The wilderness-wandering Cain of Fear the Walking Dead, Troy Otto, devised a plan to direct a horde of walkers (in Fear parlance, "infected") to swarm the ranch and kill the people he felt had wronged him. He snuck back onto the ranch and warned Nick that something was coming. The next day, Nick and Jake went out to investigate, and saw Nick directing the horde. They went to stop him, and Jake pointed a gun at Troy's head, telling him, "I'll kill you, brother, I will."
But Nick wouldn't let him, and he knocked Jake down a hill into the stream of walkers. Nick and Troy jumped down to rescue him, but Jake got bit on the arm in the scuffle. Meanwhile, the horde reached the ranch. Nick chopped Jake's arm off to try to stop the spread of the infection and they tried to drive back to the ranch, but they didn't make it before Jake perished and turned.
Jake's death means that the Broke Jaw survivors are without a designated leader and the Otto reign is over, since Troy will never be in charge. The balance of power on the ranch has shifted entirely to the Nation, which means Alicia's (Alyica Debnam-Carey) diplomacy will be more crucial than ever.
Inside the ranch, Alicia led the survivors down into the pantry bunker. They're trapped down there. So now it's up to Nick and Troy to save everyone Troy just tried to kill. And it's up to Alicia to lead the remnants of the ranch, both white and Native American, until Madison (Kim Dickens) and Walker (Michael Greyeyes) get back. When they return, they'll have plenty of water, but no ranch to supply it to.
Fear the Walking Dead airs Sundays at 9/8c on AMC.