The mystery of a third Summers brother started way back in 1993's X-Men #23, thanks to a slip of the tongue by Mister Sinister when talking to Scott Summers/Cyclops about his family. Sinister corrects himself to state he was only speaking about Scott's brother Alex/Havok, but the seeds of other siblings were already planted.
When Gabriel Summers was revealed in the pages of X-Men: Deadly Genesis, the mystery was apparently resolved, though rumors of more Summers siblings still persist. Gabriel Summers, or Vulcan as he is now known, is set to play an important role in the upcoming "Dawn of X" relaunch, so it's a good time to get to know Vulcan, the third Summers brother.
10 ARTIFICIALLY AGED
Gabriel Summers stared life roughly upon the death of his mother, Katherine Summers, after her and her husband had been taken aboard D'Ken's Shi'ar cruiser. Katherine was killed to punish her husband, Major Christopher Summers, for one of their escape attempts.
Gabriel was pulled from his mother's body and aged at an increased rate using Shi'ar technology. he was then sent back to Earth to become a slave for the alien invader Erik the Red. The accelerated aging negated much of Gabriel's childhood, and as an adult, he still behaves with a very youthful attitude.
9 ONE OF THE FIRST X-MEN
Gabriel was able to escape from his Shi'ar enslavers once he was on Earth, where he was found by Moira Mactaggart with almost no memory of who he was or where he came from. She helped raise him and four other mutants at her facility on Muir Island.
As revealed in Deadly Genesis, Gabriel and his fellow students were drafted by Professor Xavier as the second team of X-Men before the team he later assembled in Giant-Size X-Men. That team included characters like Wolverine and Storm and was considered the official second team of X-Men before Gabriel's past was revealed.
8 KILLED BY KRAKOA
While the X-Men are currently living on and working with the mutant island of Krakoa, the relationship between it and the X-Men started off very poorly. Upon the team's first contact with the island, the X-Men were defeated and captured by the island. Xavier was forced to use Moira's students as his first rescue mission, and implanted years worth of training telepathically.
When Vulcan and his teammates Darwin, Sway, and Petra arrive at the island, it reacted negatively to the energies of Vulcan and appeared to have killed the entire team. Xavier wiped the memory from everyone involved after Scott had trouble dealing with the loss of his recently discovered brother.
7 CAN MANIPULATE ENERGY
Vulcan displayed very high levels of power at a young age, and he exhibited the abilities to manipulate energy at extreme levels, while also being able to absorb, store, and generate energy of his own when sufficiently charged up.
Vulcan is able to use this energy in a variety of ways, including flight, super strength, energy beams, and has even shown the ability to control other people's powers by tapping into their energy source. He is able to survive in space without sustenance provided he has absorbed enough energy.
6 OMEGA-LEVEL MUTANT
Gabriel is an incredibly powerful mutant and was recently confirmed as an Omega-Level mutant by Jonathan Hickman in the House of X/Powers of X event series. This means that his power potential dwarfs most other mutants, which has made him a huge threat to the X-Men given his rocky relationship with Xavier.
Vulcan is so powerful that he may even be immortal, as was shown when it was revealed that he survived death by Krakoa due to absorbing the energies generated by his dying comrades. Even when Krakoa was launched into space in Giant-Size X-Men #1, Gabriel managed to survive dormant due to absorbing the energy of fellow mutant Darwin.
5 TOOK ON THE SHI'AR EMPIRE
Vulcan was awakened from the dormant state he was left in after Krakoa due to absorbing some of the huge amounts of energy released during M-Day, which saw a number of mutants lose their power. After Vulcan confronted Xavier about their past and fought with the X-Men, Gabriel left for space to confront his own recently unlocked history with the Shi'ar.
Vulcan would truly showcase his power when he waged war on the Shi'ar and their extremely powerful Imperial Guard, and he eventually won the support of the Shi'ar people who had ruined his life as a child. Vulcan impressed them in battle due to his power and tactics that swayed the warrior people and led to his acceptance.
4 MARRIED TO DEATHBIRD
Of course, it was also his relationship with Deathbird, an exiled member of the Shi'ar Royal Family, that helped win him over to the Shi'ar Imperium. The two met when they were escaping a prison moon together, and were soon married by Emperor D'Ken, who Vulcan had recently healed despite his desire for vengeance for the murder of his mother.
However, following the marriage to Deathbird, Vulcan killed D'Ken and took final and complete control of the Shi'ar Empire, now gaining the Imperial Guard as loyal followers instead of dedicated enemies. His rule would be opposed, however...
3 AT WAR WITH HIS FAMILY
While Cyclops and Gabriel had issues following the death of some X-Men and his treatment of the rest in Deadly Genesis, it was Havok who took it upon himself to chase Vulcan down in the Shi'ar Imperium. There his team of X-Men teamed up with the Starjammers and former Empress Lilandra to take the fight to Vulcan.
Following Vulcan's marriage ceremony where Gabriel murdered their father Corsair, the leader of the Starjammers, Havok continued the fight against his younger brother, alongside Rachel Summers, Gabriel and Alex's niece from the future. Their familial ties only angered Vulcan more, as he blamed their ignorance for his tragic life.
2 FOUGHT IN THE WAR OF KINGS
Vulcan's rule of the Shi'ar Empire was also opposed by the other galactic rulers as Gabriel sought to expand his rule over the rest of the Marvel universe. This brought him into direct conflict with the newest rulers of the Kree Empire, the Inhuman Royal Family.
The Inhumans origins came at the hands of Kree experimentation, so when Black Bolt and his people left Earth, they united the various other Inhuman races created by the Kree and took over the struggling empire. Black Bolt and Vulcan were assumed dead following an explosion in space that ripped a hole in the fabric of the universe. Black Bolt returned, but Vulcan's fate was unknown.
1 WILL REJOIN THE X-MEN
While Vulcan's reasons behind his return are unknown, he has been revealed as an Omega-Level mutant who currently resides on the island of Krakoa with the rest of the mutant population. The fact that he is on Krakoa is interesting enough, and we can't wait to see that explored more.
And fans will get the chance to learn all about Vulcan in the "Dawn of X" as he is slated to appear alongside his brothers in the new X-Men series from Jonathon Hickman and Leinel Francis Yu. Considering the previously discussed hatred that exists between Vulcan and his family, his place among the X-Men should make for an interesting read, at the very least.