BIOGRAPHY
Sobunar is from a line of aquatic mutants. His mother and grandfather both had the same name and presumably the same or similar powers. [X-Men: Red (2nd series) #1] His family were from Arakko, the remnants of the former mutant homeland of Okkara. Thousands of years ago, Okkara was split in two, Arakko and Krakoa. Those on Arakko found themselves trapped in Otherworld, fighting an unending battle for millennia against the demons of Amenth. Following the end of the X-Swords event, Arakko had been transported back to Earth. Sobunar was part of the present-day ruling council of these Arakkii mutants, the Great Ring. Being an omega level mutant was a requirement for membership and he was sublimely powerful. His seat was called “the seat of below us.”
[Note: Given that he notes that his mother and grandfather had the same name and he also refers to his own “offspring,” it possible he is the result of asexual reproduction.]
The mutants of Arakko were incredibly warlike and concerns mounted over their presence on Earth. A decision was made to terraform Mars and create a mutant planet primarily to house them. Magneto led the charge on this project and went to Arakko to meet Sobunar and some of the others who were key to the success of this endeavor. Fortunately, Sobunar agreed and departed for Mars. His blood contained an ocean inside it. One drop and Mars now had water. Of course, he was merely one of many omega level mutants whose gifts made the former red planet habitable. Lactura, another of the council, transported the island Arakko and all of its inhabitants to Mars, which they naturally renamed Arakko. In the aftermath, Sobunar seemed quite proud, boasting that the oceans were teeming with his offspring; which would evolve and go on to make war as all Arakkii did. [Planet-Size X-Men #1]
Storm was appointed regent of Arakko and she was some
what of a controversial figure among the Great Ring. Some of the other members felt they needed to return to Amenth to wage war alongside their former leader, Genesis. When a vote was taken, Sobunar stood with Storm and decided to try peace for a change. The vote was deadlocked and Storm as regent got a second vote, and again voted for peace. [X-Men: Red (2nd series) #1]
This window of “relative” tranquility was very short lived. The Eternals race launched an attack on Arakko using a variety of different technological weapons. The greatest threat, however, came from their former ruler, Uranos, who was unleashed on the planet for just one hour, intending to cause as much damage as he could. He appeared in front of the Great Ring, just as they were being debriefed by Cable and Abigail Brand of the threat. As he was ‘porting in, Isca the unbeaten decapitated another member of the Ring, Idyll. Her mutant ability was to never lose so, she had defaulted to the winning side of Uranos. Nightcrawler quickly attempted to take her off the board by teleporting away with her and dropping her in the ocean. Sobunar was tasked with protecting the oceans from the many Eternal weapons besieging it, while his creatures would futilely face off against Isca and keep her busy. It was to be up to other members of the Ring to try and fell the mad god. [X-Men: Red (2nd series) #5]
Storm had been off world but retrieved Sobunar when she arrived back. Sobunar was a natural partner for Storm, as he flooded the air with water. Storm would use the ambient moisture to enhance her lightning, bringing down mighty weapons. Storm was beating herself up over not being there when Uranos initially attacked. Sobunar actually consoled her, repeating an old “prison” expression to her: “if you weren't there, you were somewhere, fighting the same foe.” He meant that they had far too many enemies to turn on themselves internally. Storm was reassured by his words. Sobunar, Storm and Lactura soon met up with the others preparing to the take the fight to Uranos himself. [X-Men: Red (2nd series) #6]
Storm, Legion and Magneto did manage to defeat Uranos and destroy the machines attacking Arakko, though Magneto died in the process. In the aftermath, Isca was persona non gratis among the Ring. In living memory, none of their own had killed another member outside of an actual challenge. Expulsion was being considered. Isca was furious and goaded them into attacking her. With her mutant ability to never lose, she would simply kill them all. Sobunar made it clear he or rather they did not fear death. Isca opted to resign anyway, once it was pointed out to her that her mutant ability to never lose made it so she also had never actually won either. With so many of their members either dead or expelled, it was time for something new. [X-Men: Red (2nd series) #7, Legion of X #6]
Sobunar at this point was committed to change. When Storm was challenged by Vulcan to single combat, for example, he aided her in her battle, something previously for an Arakkii mutant that would have been unthinkable. [X-Men: Red (2nd series) #10]
Change is hard, however, and Sobunar did falter. The former Arakkii leader, Genesis, returned after Uranos' attack. She was disgusted by what had happened to the Ring. She felt that Storm's influence had weakened them. Genesis was also under the thrall of a demon named “Annihilation,” which was contained inside a staff she wielded. Genesis (or rather Annihilation) through its “whispers” managed to shame Sobunar for “betraying” their peoples' values. 
He was even muttering that they were all cowards. Genesis was a vitriolic character and, soon at odds with two of Storm's other loyalists, was about to smite them down. Storm was furious and was about to interject when Sobunar attacked. He believed her “honeyed” words had seduced them and challenged her to single combat. Given how volatile the situation had become, Lactura teleported Storm and the others away, stopping all the fights before they could begin in earnest, including Sobunar vs Storm. [X-Men: Red (2nd series) #13]
[Note: It was unclear but, given the sea change in Sobunar’s loyalties, it appeared Annihilation was influencing him, as well as Genesis. Prior to this moment, he had been one of Storm's greatest allies among the Arakkii mutants.]
Sobunar remained by Genesis’ side, though even with Annihilation's terrible influence on him he had some objections. Genesis had intended to use his “children” in the ocean as weapons and claimed they were beyond her remit. Genesis, however, did simply overrule him, as they were at war. One of his more powerful children was dispatched to fight Storm, though she killed it easily. [X-Men: Red (2nd series) #14] Ultimately, Storm’s forces did prevail. She destroyed Annihilation and Genesis was exiled from Arakko. Afterwards, Sobunar opted to become a hermit, remaining under the ocean. Whether he will return remains to be seen. [X-Men Red (2nd series) #17-18]