Jaxon Merak was a highly skilled engineer-turned-businessman who owned and operated a successful transport company off of Diem, a small planet in the Outer rim. In his spare time, he could be found in his shop, building a technologically advanced mechanical spider-frame—a project he kept well hidden save for his equally engineering-adept aide—as well as robotic prosthetic limbs he'd give out to those members of his community who'd suffered crippling accidents.
He led a good life, until the Imperials, led by the infamous Admiral Tarus Denhoff, decided to raid Diem for resources. When they came across Jaxon, they were amazed by his creations, and the Admiral extended him an invitation to join them as a weapons engineer. When he declined, Denhoff suddenly demanded that Jaxon's aide be turned over to him.
This perplexed Jaxon, as he hadn't thought much of his aide's personal life outside of the workshop where the two created their wares, and his aide had left the planet a week prior rather hurriedly and with no explanation. He supposed there was quite a bit about his aide he hadn't even tried to know, as his helper's skills mirrored his own and all of his energy and attention was focused on creation of their wondrous mechanics. When Jaxon questioned the issue with the Admiral's insistence, he was told that his now missing assistant was a Rebel agent, and that Jaxon was now considered a Rebel sympathizer for refusing to turn him into the proper authorities. Denhoff ordered his troops to kill everyone and raze the town for aiding and abetting a Rebel.
Through nothing less than a miracle, Jaxon survived by jumping inside a bacta tank he kept in his lab, but his body was maimed and crippled way beyond the limits of medical technology. He'd lost half his torso, both legs, and one eye. The tank's computer gave him, at most, six months to live. Whilst he pondered his fate floating in bacta, he had a vision of his brother, who he hadn't seen since he set off on a pilgrimage to find enlightenment through the B'omarr monks, who purportedly lived in the deserts of Diem. This could have been a fever dream brought on by the massive recent trauma he'd been subjected to, but some strong inkling led him to believe it as actually happening.
Jaxon knew the grim legends surrounding the B'omarr, but he had nothing left to lose. The worst that could happen was a lifetime spent inside a jar in a dark cellar of the B'omarr monastery. He preferred that alternative to death, for even in such a situation, being alive meant there was still hope. Unfortunately, almost all of his former acquaintances or customers were now dead or wouldn't touch him due to his status as a Rebel sympathizer. However, a mysterious benefactor provided information anonymously—and with copious amounts of credits from his own accounts—he found the monastery of the B'omarr Order.
Jaxon arrived aboard his spider-mech—aboard being a relative term—and the monks were surprised to see such a machine in the hands of an unenlightened human. He explained his body had not long to live, and that he wished his brain to be installed in it, so he could one day achieve enlightenment himself. He made sure to point out that death meant enlightenment was impossible. In exchange, he would become the protector of the monastery, ensuring no one would disturb them ever again.
After much deliberation, the B'omarr agreed on the principle that the death of someone who sought enlightenment, even if that meant trespassing into the realm of the unorthodox, was wrong. The monks explained to Jaxon that an Imperial battlegroup had been harassing them, going so far as hunting down their brothers. Jaxon was delighted to find out that Admiral Denhoff was the leader of said battlegroup. He offered to bring the brain of the Admiral for the monks to do as they pleased with it.
That day, Jaxon Merak was reborn as an eight-legged war machine. Once he got used to his new self, he set off to hunt. After three days and two nights, the prodigal brother returned. His plating had laser scoring and a few dents here and there, but remained, for all intents and purposes, undamaged. Jaxon used one of his mechanical appendages to pull out a jar from one of the spider-mech's storage compartments. It was the brain of the Admiral, destined to live the rest of his life cut off from all sensation, and in complete isolation—or whatever horrific fate the monks could cook up. He didn't care, his vengeance was complete.
Later that evening, Jaxon heard a very familiar voice in his head. It guided him into the monastery catacombs. There were rows upon rows of brains in fluid-filled jars neatly organized in slots built into the walls. Quite the sight. Jaxon walked slowly, looking around and feeling strangely at home. After all, he was no different from them. When the voice told him to stop, he would've shed tears if he could. The brain floating in front of him was his brother, Gil Merak. It was a strange reunion, but a happy one. The brothers conversed. It was the first of many enlightening conversations.
During the following seven years, pirates, raiders, and warlords tried to seize the monastery. They failed. The legend said that upon hostile intent, a scarred gunmetal spider would materialize from thin air to dole out brutal and deadly punishments to trespassers. It was common knowledge that the lucky ones died outright, while the unlucky ones became part of the B'omarr's collection—whatever that might mean. The legend of the ghostly spider-bot spread, and eventually reached the ears of somebody that knew it was more than just a ghost story meant to ward off predators looking to sack a monastery.
One day, the monks informed Jaxon that a visitor was awaiting him outside of the monastery. Unsure of the intent of the visitor, he geared up for battle and charged forth to meet whatever awaited him. As he preemptively spooled up his rotary cannons, the face of the visitor came into view and stopped what now served as his heart dead in its tracks. His long lost aide had found him! After a long conversation, his aide had confessed that the Admiral's accusations were true, and he was indeed a Rebel agent. He also confessed to being the mysterious benefactor that had provided him the information he needed to find the monks to prolong his life. He apologized for not being more forthright with his ties to the old Rebel Alliance, as he was working with Jaxon to learn more about prosthetics so that he could take that knowledge to help the downtrodden populaces that were in need. He was back now because yet again they could use help in their final push against the Empire, and Jaxon was just what they needed to push back against the Empire on the ground while the fleets attempted to do the same in space.
Jaxon, wanting to take the fight to the Imperials, asked the elders for the opportunity to leave the monastery for a while in order to join the New Republic. The elders unanimously agreed that it was just a matter of time for the Empire to become a threat to the B'omarr, and allowed Jaxon to leave with their blessing. During his tenure as a protector of the monastery, Jaxon spent seven grueling years fighting the scum of the galaxy, becoming one with his new body in the process. He is now the spider, able to identify fortuitous ambush locations and dig himself into the ground to lay in wait for his enemies to stumble upon his killing field. Jaxon is a deadly ambush predator, devastating artillery unit, and stalwart frontline fighter who's honed himself into a powerful weapon. With his old aide paving the way for him to join the New Republic, he will now fight to expunge their evil from the galaxy.