Warning: This article contains spoilers for Avengers #27
The Mighty the parasitic alien race known as the Brood. Earth's Mightiest Heroes may usually act in the defense of their homeworld, but they've developed something of a reputation across the galaxy. They've traditionally been considered meddlers, cosmic interlopers who've caused frustration for some of the greatest empires in the galaxy, but in recent years that has changed.
It was all a result of 2013's Infinity event, in which a cosmic force known as the Builders cut a bloody swathe across the galaxy, heading straight for Earth. The Avengers were called to a coalition of forces who fought against the Builders, and they impressed the galactic empires with their courage and fortitude. The Builders were only defeated because of Captain America's leadership, and ever since the Avengers have been on call whenever various alien races have been out of their depth. In Avengers #27, the powerful alien called Gladiator - currently regent of the Shi'ar Empire - calls them for help on a mission that goes badly wrong.
A cosmic force known as the Starbrand has arisen inside a Shi'ar maximum security prison, and Gladiator has disappeared after heading in to deal with the crisis. The Avengers rush to the scene, curious to learn what's going on with the Starbrand, but unfortunately their mission goes wrong pretty much straightaway. The inmates have taken over the prison, and they've set up magnetic webs to capture any spacecraft that approaches. Although the Avengers are able to drive their enemies back and keep their ship, they can't break free - and Thor pays a massive price for his heroism when he's infected by the Brood.
The Brood are traditionally enemies of the Ghost Rider. This time round, though, they've achieved their greatest success; they've successfully transformed Thor Odinson into a Brood. The new All-Father of Asgard desperately resists for a time, but by the end of Avengers #27 his resolve has crumbled and he's been fully transformed into a Brood.
The Brood have always been considered one of the most dangerous races in the galaxy, but Thor's conquest will make them a real power-player. The aliens possess a hive mind, and all a host's knowledge is incorporated into it. That means the Brood haven't just gained a Thor-powered host; they now know everything Thor has ever known, and have full access to his memories. Presumably there's a Brood Queen in the prison, and she's just gotten a massive power-up.
Avengers #27 is on sale now in comic book stores.
