Both DC and Marvel have been absolutely slaying on the small screen in recent years – from DC’s hugely successful Arrowverse shows to Marvel’s Agents of SHIELD and Netflix handful of Defenders series, comic books and superheroes are just as popular on TV as in the movies. However, one of the biggest comic book franchises has yet to make an appearance – Fox’s X-Men. Despite having sixteen years of movies under their belt, the live-action X-Men were noticeably absent from television… until now.

Early next year, FX will be premiering the first X-Universe show: Legion. Starring Dan Stevens as David Haller (aka Legion), the show will focus on Legion’s journey as he realizes that his diagnosis of schizophrenia may be incorrect – and that the voices in his head are because he is a mutant. The series will not be linked to the cinematic universe, according to Simon Kinberg, and will have a very different tone to the X-Men adventures on the big screen. While few details about the show have been released so far, what we do know has fans intrigued. If you aren’t already a fan of Legion from the comics, though, we’ve rounded up everything you need to know – including several elements we are sure to see in the series, and some we are definitely not.

14. He Created The Age Of Apocalypse Timeline

Age of Apocalypse is an alternate timeline (not to be confused with the most recent movie, X-Men: Apocalypse) in which Xavier died years ago, Magneto is the leader of the X-Men, and Apocalypse has taken over the world. It’s a dark and dangerous world for both mutants and humans, and its existence is the doing of David Haller. In an attempt to realize Professor X’s ultimate vision of a world where human and mutant kind live in harmony, Legion opens a time portal, intending to go back in time and kill Magneto. Unfortunately, he fails in his quest, as a younger Charles Xavier leaps between Legion and Magneto in the final moments of their battle. Xavier takes the killing blow meant for Magneto, and his death marks the beginning of the Age of Apocalypse timeline. Although the timeline was eventually restored, Legion (temporarily) lost his life in the process – and Age of Apocalypse remains his claim to fame (for better or for worse).

13. He is Charles Xavier’s Son

During Charles Xavier’s early years, before he became the legendary Professor X, Charles spent time in Israel. While there, the telepath visited a clinic for survivors of the Holocaust, where he met two people who would have an enormous impact on his life. The first was Eric Lehnsherr, who would later become Magneto – his sometimes friend, and greatest enemy. The second was Gabrielle Haller. While Eric was working at the clinic, Gabrielle was a patient there. A survivor of the concentration camps, her mind had been severely damaged, and she was left in a coma. Charles, using his abilities, was able to cure her, and the two fell in love. During this time, Gabrielle conceived a child – David Charles Haller. She didn’t tell Charles of her pregnancy, and he didn’t learn that he had a son until David’s teenage years. However, Legion is clearly his parents’ child. He inherited his father’s immense power, but unfortunately also inherited some of his mother’s mental instability – the two creating the unique mutation that is Legion.

12. His Powers First Appeared As A Child

Like many mutants, David Haller’s powers didn’t reveal themselves until he was approaching his teenage years. As a child, David was a kind and gentle child, but a tragedy forced his powers to assert themselves in the worst possible way. Gabrille Haller became a member of the Israel diplomatic service, and David lived with her and his step-father (Daniel Shomron) in Paris. Their happiness was shattered one day when a terrorist organization sent assassins to their home, hoping to kill any Israelis that they could find. They murdered David’s step-father in front of him, and the trauma of that event had a two-fold affect. It splintered David’s mind, and rendered him catatonic. However, it also awoke his considerable powers, allowing him to use his mind to destroy the brains of the attackers. To heap trauma on top of trauma, David’s mind was linked to his attackers’ as he murdered them, allowing him to feel their fear and pain as they died.

11. He Can Absorb Others’ Consciousness

When David’s power’s first manifested, he learned that not only was he capable of telepathy and psionic blasts (among other powers that we’ll cover later), but that his mind could actually absorb the consciousness of another human. The first person to be absorbed into Legion’s mind was the leader of the assassins who murdered his stepfather – Jemail Karami. Karami was able to retain his sense of self, despite now being merged into David’s mind, and was instrumental in healing David’s mind to the extent that David regained his awareness. Karami had become a persona in David’s mind, with access to his telepathic powers. Other powers had become attached to different personas created by David’s mind, and the battle to heal David’s mind was not entirely won.

10. He Was Cared For By Moira McTaggert

After David recovered from the catatonic state that he was initially left in after his powers manifested, he was still struggling to cope with his new reality. His mother, Gabrille, sent him to live on Muir Island with Moira McTaggert, believing that Moira would be the best person to care for David. However, while there, his powers began to manifest in the real world, not just in his mindscape. Unable to control himself, he absorbs the consciousness of several people on the island, including research associates, New Mutant team members, and Moira herself (these were returned to their bodies, in the end). It was during this time that Charles Xavier came to the island, and learned that Legion was his son.

9. His Mind Is Host To Multiple Personas and Powers

This is the heart and soul of Legion’s powers – that the trauma David’s mind endured damaged it severely, creating multiple personalities, each with control over a different element of his powers. On top of the personas originally created by David’s own mind, his ability to absorb the consciousness of others has added additional personas at various times during his life. At times, various personas have taken over David’s body, which is one of the most dangerous elements of his mutation. These multiple personas are something that we are guaranteed to see in the upcoming TV series, whether his origin story is kept the same in the show or not, we will absolutely be seeing David deal with multiple personalities and powers.

8. Some Of His Personas Are Stronger Than Others

Although Legion has a vast number of different personas within his mind, there are certain personas that are stronger than others. These are the personas that are most likely to take over David’s body as Legion, and are the hardest for him to control. Karami’s persona (the first that he absorbed) is one of the most powerful, having retained his sense of self. The two other most powerful personas in Legion came to light when Karami failed to re-integrate all of David’s splintered personas with his core persona. One persona goes by the name of Jack Wayne, an arrogant and swaggering adult, who controls David’s telekinesis. The second is Cyndi, a younger female persona with an attitude problem and control over David’s pyrokinesis. Other personas include Styx, Chain, Endgame, Susan in Sunshine, Time Sink and The Bleeding Image.

7. A Lot Of His Story Takes Place Within His Own Mind

Given the fact that David’s powers are linked to the different personas in his mind, much of his story takes place within that mind itself. The world of David’s shattered psyche is called his mindscape, and throughout the comics, story arcs and events have shown his mindscape to appear as a physical space, with his various personas walking around as individuals. When Karami first attempted to heal David’s mind, and came up against opposition from other personas, the mindscape looked like a literal warzone. When a consciousness is absorbed by David’s mind, that person appears in the mindscape (usually looking the way they do in the real world). We don’t know yet whether or not this will translate to the small screen, but it’s safe to assume that we will see some version of the mindscape in the new show.

6. He Has A Huge Range Of Powers

Unlike many other mutants in the X-Men universe, Legion has a vast range of powers (most of which are based in psionic/mental abilities). Although each of these is attached to a different persona, Legion has occasionally been able to access all his powers at once at times where his mind has been whole. Legion can also access the memories, skills and abilities of any consciousness that he has absorbed, allowing his abilities to change. Some of the powers he has exhibited so far have been: telepathy, telekinesis, pyrokinesis, sonic blasts, psionic blasts and blades, shape-shifting, teleportation, flight, time manipulation and travel, inter-reality and interstellar travel, x-ray vision, healing, super strength, super speed and a prehensile tongue. This huge range allows for the series to touch on any or all powers that they choose, and to add new powers at any time, which is sure to make for a wild ride.

5. He Is An Omega Level Mutant

In the comic book universe, an Omega level mutant is one whose power appears limitless. These mutants are rare, and incredibly powerful. With his vast range of inherent powers, it is not surprising that David Haller is classed as an Omega level. Because of his multiple personas, he may even have more powers that have yet to manifest in a dominant persona. This, combined with his ability to absorb the consciousness of other mutants and access their powers makes his abilities near-limitless. As with many other Omegas, however, there are functional limits on his powers that prevent Legion from destroying the universe. In this case, it is the multiple personas – with Legion rarely able to access all of his powers at once, he becomes limited by the personas that he can access and control. (Other Omega level mutants include Jean Grey, Hope Summers, Franklin Richards and Emma Frost.)

4. He Has Been A Member Of The X-Men

During his time on Muir Island, he became a member of the X-men team based there. However, this ended badly, as his attempts to locate missing mutants using Cerebro attracted the attention of the Shadow King. Legion was used by the Shadow King, allowing him to possess everyone on the island. Since this first, ill-fated attempt at being a member of the team, Legion has been more often foe than friend. The X-Men battled him during his attempt to go back in time and kill Magneto, and the New Mutants went up against him as well. However, at other times, the X-Men have helped Legion, especially at times that he has had a reasonable control over his ability. While he is too unstable to become a permanent member of the team, his parentage and his core personality’s desire to do good keep bringing him back to the X-Men.

3. He Is Neither Good Nor Bad (Or Is Both)

It’s not uncommon for X-Men characters to live in the grey zone between good and bad, or to switch sides from time to time. Legion is a character who has been both “good” and “bad’ in the past, and has taken both positions to extremes. One of the reasons for this lies in his multiple personalities. When a single persona is able to assume control of David’s body, that persona may have a different allegiance, causing Legion to change sides for a time. At other times, his attempts to do good have had terrifying consequences – most notably, the actions that led to the creation of the Age of Apocalypse timeline. However, when David has control over his personas, he is generally one of the good guys, and often horrified by the things that his other personas have done.

2. He Is A Killer

Although David is essentially good, when he does not have control over his personas, he has been known to kill. Starting with the men who attacked his home and killed his step-father, Legion has racked up quite a few kills over the years – even without considering the vast numbers who were killed in the Age of Apocalypse timeline. He has killed the parents of a young mutant named Marci, obliterated Gods (literally), and killed Charles Xavier (in an attempt to kill Magneto). However, his most famous murder was that of Destiny – a mutant precog whom Mystique loved. He telepathically attacked her on Muir Island, and when that attack showed him the horrors of the Age of Apocalypse timeline, he snapped and murdered her with a telepathic blast. To make things even more horrifying, he then telepathically broadcast her death to Mystique, and absorbed her consciousness. The events surrounding this leave Legion in a coma, and Mystique hungry for revenge.

1. There Are Ways For Him To Control His Powers

Legion’s biggest problems stem from his multiple personas and his inability to successfully control them. However, over the years, there have been several attempts made to harness his abilities – some more successful than others. When a young Marci is trapped within Legion’s consciousness, a doll that she is carrying enables the persona holding it to take over Legion – with terrible consequences, as the doll is within Legion’s mindspace, and when a malevolent persona has it, that persona can control the body. Later on, we learned that David has a “Persona Brig” – a prison for his worst personas. Professor X developed a helmet that allowed them to control which persona is dominant, allowing Legion to aid the X-Men temporarily, but this is not a long-term solution. A neural switchboard was also created, which allowed Legion to access powers without needing the attached persona to take control. Others have attempted to kill Legion’s other personas, re-integrate them, heal him or even give him mystic training to be able to control his personas himself. However, none of these have been successful in the long term, and he lives in fear that he will lose control again.