In the background, many critics of the regime, abducted by anonymous men in white vans, vanished from sight. The editor of the liberal weekly Sunday Leader, Lasantha Wickrematunge, who had antagonized the government with his unrelenting coverage of its excesses, was shot dead on his way to work by masked gunmen on motorbikes in early 2009.

The Rajapaksas lost power in the 2015 elections after lawmakers within their party abruptly jumped ship and joined a broad coalition against the government. But the unity of purpose that endeared the rebels to voters collapsed under the weight of internal squabbles once they were elected to government.

The tyranny of the Rajapaksas was replaced by squalid spectacles of quarreling between the new president, Maithrapala Sirisena, and his prime minister Ranil Wickremesinghe. Their feud grew into a constitutional crisis in 2018 when President Sirisena fired the prime minister and realigned himself with the Rajapaksas to shore up his precarious political power. He offered the prime minister’s position to Mahinda Rajapaksa but the courts declared the move unconstitutional.

The Rajapaksas, discredited, appeared poised for obsolescence. What rescued them were the coordinated suicide bombings at churches and luxury hotels on April 21, Easter Sunday — 259 were killed and more than 500 injured — by self-radicalized local Muslims who claimed to be affiliated to the Islamic State. Riots erupted in multiple parts of the country as it became apparent that the incompetent government, consumed by infighting, had neglected warnings by India and the United States of an imminent terror attack. Muslim businesses were vandalized and ordinary Muslims were attacked.

Gotabaya Rajapaksa announced his candidacy four months after the explosions and mounted his comeback on the fear and rage that pervaded Sri Lanka. For Sri Lanka’s minorities, the scale of Mr. Rajapaksa’s victory — winning nearly seven million votes — was terrifying because it revealed the full capacity of a campaign premised on chauvinism to mobilize the majority.

Colombo, lashed by thunderstorms, was dark and damp on the day Mr. Rajapaksa was sworn in as president. He chose to hold his inauguration in Anuradhapura, an ancient Buddhist town where a Sinhalese king had defeated a Tamil invader more than 2,000 years ago.

The location was a declaration of the Rajapaksas’ majoritarian leanings. Blessed by Buddhist monks, Mr. Rajapaksa affirmed his support for their dream of a Buddhist-first Sri Lanka and chided minorities who failed his “expectations” by voting against him. His first act as president was to appoint the prime minister of Sri Lanka: His brother Mahinda Rajapaksa.