"Look, every one of you hates every one of us, and we hate you right back. Let's get at it!"
(~Bernardo to Riff and the Jets at the rumble)
Bernardo is a Puerto Rican migrant and founder and leader of the Sharks, a Hispanic street gang who are in the midst of a turf war with their archenemies, the Jets. He is the older brother of Maria and is Anita's boyfriend.
Bernardo's character is based partly on Tybalt (Juliet's cousin) from Shakespeare's Romeo & Juliet; compared to Tybalt, Bernardo is just as intolerant of his enemies, but more level-headed. Tybalt's short temper was delegated to the character of Action.
Coming to America
In an attempt to make a better life for himself and his family, Bernardo immigrated to the mainland before Maria. After Maria's arrival, Bernardo becomes her protector and, to her annoyance, often lords his status as older brother over her. Over time, he begins to regret coming to America, and he, Anita, and the rest of the Sharks and their girls do a lively song-and-dance comparing life in America to the way things were back in Puerto Rico ("America").
Bernardo developed a dislike for Americans after he was attacked by members of the Jets the day he arrived in New York. He decided he would form his own street gang which he named the Sharks. Under Bernardo's leadership, the Sharks became a formidable gang in the Manhattan neighborhood of Lincoln Square and eventually become the number one rival gang to the Jets. His hatred flares up for the Jets after he catches Maria and Tony kiss for the first time when they meet at the dance. After he sends Maria home he is about to go after Tony, but he is blocked by Riff, who cajoles Bernardo into a war council (a meeting to determine logistics for a planned rumble); the two leaders agree to meet at Doc's Drug Store.
During the war council, Bernardo and Riff are discussing weapons when Tony comes in and reminds them that a rumble can be clinched by a fair fight- to wit, the best fighter from each gang to slug it out one-on-one, winner take all; over objections from other members of both gangs, Bernardo accepts, thinking that he will be fighting Tony, but Riff, knowing that Tony is not a current member of the Jets, hoodwinks Bernardo and puts forth Ice as the Jets' champion.
At the rumble, Bernardo and Ice are just starting when Tony arrives to attempt to stop the fight, but when Bernardo and the Sharks mock Tony and call him "chicken", Riff, unwilling to see Tony humiliated, steps in and slugs Bernardo, and both gang leaders whip out switchblades and begin fighting one another. Tony again attempts to stop the fighting by pulling Riff back, but Riff breaks away from Tony and charges again, only to be stabbed in the ribs by Bernardo. In an angry fit of vengeance, Tony takes Riff's switchblade and stabs Bernardo, killing him.