Superheroes encounter horror-themed stories from time to time, but their powers often keep them ahead of whatever monsters threaten them. But against something as fearsome as the Brood, not even optic blasts or organic steel can save you.

What happened to the X-Men during the original "Brood Saga" by Chris Claremont, Dave Cockrum, Bob Wiacek, Tom Orzechowski and Glynis Wein -- and how does it stand out as one of the best superhero horror stories ever?

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Taking place throughout Uncanny X-Men #161-167, the story begins as the X-Men are celebrating with Lilandra when they're attacked by her traitorous sister, Deathbird. The X-Men (Cyclops, Storm, Wolverine, Kitty Pryde, Nightcrawler, and Colossus), alongside Carol Danvers, are quickly turned over to the Brood. Although the team is initially hypnotized into believing they are just at a peaceful  Shi'Ar celebration, Wolverine's senses allow him to realize it's actually the Brood, who proceed to infect each of the X-Men with a Brood Egg that will turn each of them into Brood themselves.

Wolverine escapes, fleeing into a nearby jungle to try to fight the infection within him. He succeeds, and his healing factor burns out the Brood embryo, protecting his life and giving him the chance to return to the rest of the X-Men with knowledge of what they're up against. However, Wolverine returns to the X-Men with the harrowing news that they also have the embryos inside them -- and they don't have the healing factors to counter them.

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What follows is one of the best horror narratives that Marvel has ever produced. The Brood Eggs are an inherently frightening prospect, gestating in an unwilling host until maturity, at which point they break down the body and convert it into that of the Brood. The Brood are quick, ferocious, and ruthless in their pursuit of the X-Men, with their simple plan to expand their colony threatening the entire universe. The powers of the Brood and their means of corrupting those infected with their eggs gives the entire proceeding a paranoid edge, as there's always the chance someone has been transformed too soon and could turn on their teammates -- which turns out to be a valid fear when Cyclops does just that.

The Brood have long been some of Marvel's most frightening concepts, a take on the kind of threats one would usually see in films like Alien or The Thing. It gives a different kind of flavor to the story, a cosmic terror and hopelessness that permeates through the arc. Because that's what really separates the "Brood Saga" from other horror stories featuring superheroes: due to the trappings of the genre, overcoming impossible odds are part of any superheroes job. But against the Brood, there's a real sense of broken defeat to the X-Men. Kitty Pryde has an existential crisis while dreaming of her upcoming funeral, Nightcrawler solemnly turns to prayer, and Storm actually tries to kill herself by allowing herself to be sucked into the vacuum of space rather than become one of the Brood.

It all comes together to make the stakes more distressing and terrifying, and it turns the X-Men from infallible heroes into vulnerable humans. Even Wolverine, despite his powers keeping him impervious to the Brood conversion, is faced with a very real dilemma -- what happens when all his friends turn against him and become monsters? The story partly becomes about Wolverine facing the fact he might have to kill his new family, and that weight almost crushes him instantly. "The Brood Saga" is bleak, scary, and unexpected in the emotional depths it's willing to take. All of that combines to make it one of the best horror stories the publisher has ever put out.

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