Arthur Dearborn was a scientist who developed a cutting edge satellite to collect solar energy to help the Earth's energy needs. However, he couldn't get it financed. Eventually, he was able to convince Roxxon to build it, but they only agreed to do it if he would agree to be converted to a being of pure energy, so he could work on the satellite without constant supplies of food and water. He agreed, and worked there until Iron Man arrived. The satellite, Star Well I, had accidentally shot a beam of energy towards Earth, and killed 200 Iowans. At first Iron Man was impressed with Dearborn's scientific goals, but when it became clear that Dearborn was unapologetic about the accidental deaths he had caused, they fought. Their battle caused a chunk of it to fall towards a populated section of Earth. He helped Iron Man deflect the satellite, and seemingly died over the ocean in the process. However, his energy was merely dispersed. Roxxon built a second suit of armor in an attempt to reintegrate him, but lost the armor at sea. This armor was later found by Mike Stone, who temporarily used it to become Sunturion II (see below). After that, Roxxon made a third suit, which it gave to another employee, who took on the name Stratosfire.
However, Stratosfire became increasingly unbalanced due to the suit's energy transformation, and when she found out that Roxxon killed her best friend, she became a loose cannon. Roxxon then "resurrected" Dearborn with yet another suit, and set him against Stratosfire. Iron Man teamed up with him. The first time they fought Stratosfire, Dearborn partially absorbed her energy and forced her to fly away. During their second fight, he managed to activate an internal self-destruct mechanism in her suit, killing her. The resulting explosion also took away his own powers.
During the Stratosfire incident, Dearborn revealed that he knew Iron Man's secret identity, but pledged to keep it confidential.
During the Spider-Man Vibranium Vendetta storyline, Dearborn was still working for Roxxon, helping them create an artificial form of Vibranium called Nuform. Spider-Man, Iron Man, and Black Panther thought Roxxon was up to no good and investigated. The Ghost also showed up to sabotage Roxxon, and they all battled. Dearborn came in and was accidentally hit by a microwave blaster used in the Nuform process. This blast turned him back into Sunturion, but also affected his sanity. Spider-Man hit him with more microwave radiation, and he turned back to Dearborn, and regained his self-control. In fact, he could now once again turn into Sunturion at will.
A company man to the bottom of his heart, Dearborn didn't believe the heroes' assertions about Roxxon, and kicked them out. However, he investigated on his own, and became suspicious. Once again, Roxxon's Nuform warehouse was attacked by the Ghost, but now Ultron showed up with an army of androids as well! Dearborn tried to evacuate with the Nuform data, but Iron Man tried to force his helicopter down. Dearborn had the helicopter attack, and then turned into Sunturion to fight Iron Man himself. Neither could gain the upper hand. Finally they stopped fighting, and Iron Man left. (The Ghost and Ultron both had their own trouble and left as well.)
Ultron and his androids attacked again later, and this time Sunturion teamed up with the heroes. Sunturion fought Ultron alone, but Ultron figured out a way to twist Sunturion's ability to lock onto an opponent's energy beam and used it against Sunturion, temporarily defeating him. They battled again later, and this time Sunturion temporarily took down Ultron using his full-body energy blaze. (Ultron recovered soon after.)
The heroes found out that the Nuform was unstable and turned into Antarctic Vibranium, which would melt all the metal in the vicinity. Iron Man asked Sunturion to teleport it all into the center of the Earth, but Dearborn pathetically felt that he couldn't do it without permission from his company superiors, even though it was an emergency. Iron Man ultimately dealt with the Vibranium. Jonas Hale, the Roxxon vice president, told Dearborn that the whole mess was caused by a few bad elements in the company, and that it was all taken care of (actually, Hale masterminded the whole thing), and Dearborn happily swallowed the lie.
Mike Stone was a trucker who did a regular New York to Florida run for the mob. However, he was skimming off the top, and they fired him. While in Florida, he went fishing, and accidentally caught the Sunturion armor that Roxxon had originally intended to use to reintegrate Dearborn.
He used the suit to get revenge against his former employers. He killed a number of their goons and stole their dope, then worked his way up to his former boss, Richard Knox. However, Daredevil got there first and fought Sunturion. Sunturion was far too powerful for Daredevil and defeated him. However, Daredevil realized that Sunturion had no heartbeat, and figured out that he must be pure energy. Daredevil ripped off Sunturion's mask and Stone's energy dissipated into the air, leaving an empty suit behind. He has never been reintegrated.
Powers and Abilities
Arthur Dearborn is a highly proficient scientist and engineer, capable of designing an entire giant solar-radiation-collecting satellite that was cloaked to all technological scanning, including Iron Man's. Even Tony Stark was impressed with his technology when he visited Star Well.
Both Sunturions had similar powers, which derived from their armor, which turned them both into living energy. Their powers are also similar to those of Stratosfire. Some of the differences between the two Sunturion's powers may just be the result of Stone's lack of experience with his suit. They no longer needed food or oxygen to survive.
Sunturion I and II could appear in their armored forms or in their original human form, although in fact both forms were actually just hard energy: both the armor and the human forms were essentially a physical illusion. It is unknown whether they could make themselves look like someone else.
They could both fly; Sunturion I was able to fly markedly faster than Iron Man's Silver Centurion suit, and could survive in space. Sunturion II said he could fly to Mars.
They could both teleport instantly and easily, including in battle situations. They could teleport long and short distances.
Both Sunturions were superhumanly strong. Sunturion was able to grapple with Iron Man. Sunturion II was able to rip the roof off a bus and throw it. He also said he could juggle railroad cars. He was able to easily withstand or absorb physical attacks like punches or a hail of bullets.
Both Sunturions could project powerful blasts of radiation from their hands. Sunturion I was also able to project energy in a unidirectional sphere around him, which he could use destructively, or to blind opponents.
Sunturion I was also able to absorb energy, and was powerful enough to drain part of Stratosfire's power. He was largely immune to energy attacks. If attacked by an energy weapon, he could channel his own power back up through his opponent's energy stream, in effect absorbing their power and attacking them with his.
Sunturion I could transmute matter into energy, and absorb that energy for his own use.
Sunturion I could also use energy to control and "read" computers, even very secret and confidential ones. He was able to control Stratosfire's internal self-destruct mechanism against her will, and was able to read telecommunications information from nearby satellite transmissions.
Sunturion I was able to create energy shields, which were apparently more powerful than Iron Man's Silver Centurion's own defensive capabilities.
Sunturion I was able to turn into an intangible energy form in addition to his solid energy form.
Sunturion I was able to make holograms.
Sunturion II was able to tune into any sounds on earth, electronic or not, including human voices.