Warhammer 40,000 lore fans are in overdrive after a single page of a new campaign book teased something that’s never happened before in the setting: the meeting of two loyalist primarchs.

The primarchs are the overpowered, genetically-engineered demigod sons of the Emperor, the leaders of the loyalist Space Marine legions before they were broken up into chapters following the catastrophic civil war known as the Horus Heresy. Warhammer 40,000 as a narrative operated for decades with most of the primarchs either thought dead or lost in the warp.

Today, only two primarchs are confirmed alive and active in the current Warhammer 40,000 setting: Ultramarines boss Roboute Guilliman, who returned to the galaxy during the Gathering Storm event in 2017, and Dark Angels chief Lion El'Jonson, who miraculously popped back into existence as part of the Arks of Omen storyline in early 2023. These were galaxy-shaking plot developments for the Warhammer 40,000 setting, and ever since Lion El'Jonson’s shock return to Warhammer 40,000, fans have wondered when he’d finally bump into his brother, Roboute. Now, it looks like that long-awaited family reunion will take place in the coming months, after a new campaign book teased a meeting of the Emperor’s sons.

Word comes from Warhammer 40,000 lore expert Arbitor Ian, who IGN has partnered with for a number of explainer videos, such as the one above. Arbitor Ian got an early look at 500 Worlds: Titus, a soon to be released Warhammer 40,000 campaign book and narrative expansion that features 80 pages of lore covering the beginning of the Ultramarian Reclamation, and published a new video on its most explosive lore reveal.

To back up briefly, Lieutenant Titus from the Space Marine 2 video game has become one of the most recognizable faces in Warhammer 40,000 following its enormous success. To capitalize on Titus’ newfound fame, Games Workshop promoted him to Captain and made him Master of the Watch, which means he’s in charge of defending the 500 Worlds of Ultramar, the realm of Space Marine poster boys, the Ultramarines. With Roboute Guilliman off gallivanting with his Indomitus Crusade, Titus is now in charge of keeping things safe and sound back home, where new Necron threats have emerged, as they always do.

According to the new video from Arbitor Ian, 500 Worlds: Titus has a crucial piece of new lore, found right at the back of the book, that teases a meeting between Guilliman and Lion El'Jonson. It is an intergalactic message written by Lion El'Jonson and intended for Roboute Guilliman that reads: “Brother. We need to talk.”

This seemingly innocuous message teases a momentous plot development for the Warhammer 40,000 universe. Never before have two loyalist primarchs met in the current setting. Of course they spent a great deal of time with each other before the 41st millennium. They were, generally, pals during the glory days of the Great Crusade, for example. All the primarchs (apart from the two we don't talk about) were active during the foundational events of the Horus Heresy, which took place 10,000 years before the current setting. And we just got our first novel set during the era known as The Scouring, which saw the loyalist primarchs enact their revenge on the traitor legions in the aftermath of the Horus Heresy.

The question now is, how will this meeting between Lion El'Jonson and Roboute go? It’s hard to tell. Some fans are speculating the Lion will be a bit miffed at Roboute, who has alarmed more than a few inquisitive minds with his Indomitus Crusade. Others think (hope?) the brothers will join forces to help drive back the forces of Chaos and rekindle the glory days of the Imperium. Given this is Warhammer 40,000 and everything is… awful, I suspect that plenty will go wrong, no matter the Lion’s feelings about his brother.

And then there’s the speculation around the message itself: “Brother. We need to talk.” That doesn’t sound aggressive necessarily, but it does suggest a matter of some importance needs to be brought to Guilliman’s attention. What does the Lion know that his brother doesn’t? Does he carry a warning? Has he discovered some grand conspiracy about their father, the Emperor? Does he bring good news? Is another loyalist primarch about to return?

Arbitor Ian speculates that the Lion may be upset with Guilliman because he believes his brother to be trying to usurp the Emperor with all this Indomitus Crusade and Ultramarian Reclamation business (there’s a whole thing about Roboute potentially doing something similar during the Horus Heresy when it looked like Chaos might win). Alternatively, Arbitor Ian suggests the Lion will reveal some new threat that becomes central to the plot of the next Warhammer 40,000 campaign book, perhaps to do with would-be fifth Chaos god Vashtorr the Arkifane.

Whatever Games Workshop has up its sleeve, it looks like we’re set for some answers over the next few months. At least, that’s the hope. Fans have been waiting three years for the Lion and Guilliman to get together. If Games Workshop just sat on this tease for another few years, well… that would be very Games Workshop, wouldn’t it?

The Warhammer 40,000 story, such as it is, is a slow moving beast. The scribes at Games Workshop sometimes take years to inch the overarching plot forward. Tantalizing plot threads are left dangling, sometimes for decades. Answers remain frustratingly out of reach. Cliffhangers seem destined to hang in a perpetual state of anticipation, never to be fulfilled. Such is the nature of Games Workshop's grimdark 41st millennium, which has exploded in popularity over the last decade. At this point any news on how the story might actually move forward is analyzed to within an inch of its life, as if under investigation by the Inquisition itself.

Wesley is Director, News at IGN. Find him on Twitter at @wyp100. You can reach Wesley at wesley_yinpoole@ign.com or confidentially at wyp100@proton.me.