((Reader Warning: There is some dismemberment involved in this))
The White Fang, a faction of Faunus that sought out equality once through diplomacy and protests. Argent's family did have respect and fair discussions with their members and some smaller, lesser known leaders within the Atlas Division. But when there was a change a few years ago, the family made it a point to distance themselves from the one diplomatic faction, to the now violent, terrorist zealots they have become. This is what Argent believed for a long time, even after his mother died.
On the day his team went to visit a weapon's depot just outside the city of Atlas, the White Fang struck, lead by a human dressed in white as some of the feeling workers were shouting. This came a shock to the leader of Team ATLS and feigned surprised from the others, unbeknownst to him at the time. The White Fang of Atlas had to work in the shadows of the militaristic society, acting on ambush tactics and bombings. Atlas was at War with the White Fang, that much was obvious, but a human aiding one of their strikes?
After he told his team to split up and aid with getting the civilians out, he was approached by someone he did not expect. His own sister, Trish. She warned him that the one leading this assault was none other than Argyros Sterling, his father. Argent didn't believe it at first, but not once has she lied to him, so he wasn't going to brush this off now of all times. It explains so much though, why his letters and missives always went to faunus he didn't recognize, nor really shared much interaction with. He had to find him and stop this any way he could. With the help of his sister now, they made their way through the burning depot, striking down some White Fang soldiers along the way.
There was no sign of his team, even when he looked down to his scroll to check on their aura he was met with a shocking revelation. They were not there. Were they dead? That answer came in the form of a sharp, biting pain that cut right into his shoulder. More than just flesh, but right through to the bone and like a hot knife through butter, cut his arm and a good chunk of his shoulder clean off. His aura was already weakened before from the soldier he fought with, but Trish split off to deal with some that tried to flee. Dropping his weapon and grasping the bleeding stub in pain, he turned about to see who it was that struck him. It was Lace, a blade passing back through the portal that was made for it and on the rafters above, where a large section of the roof was torn up from, stood the rest of his team behind Argyros. His father only smirked down at his son before lifting his hand that held a detonator and shouted, "For her Grace..."
Upon pressing the button, bombs that were rigged to go off throughout various parts of the depot went off in a chain while they made their escape on one of the stolen Atlesian drop ships, Argent below vanishing among the smoke and fire. Emergency Units were quick to respond, but only to help to start suppressing the fires. Trish was outside the depot when the explosions went off, but went back inside in the aftermath to look for her brother. Found him, she did, and in very bad shape. Luckily, he wasn't near any of the bombs that went off, but the fire bursts and heat all around him from those moments covered his body in soot and minor burns, save for his left side where his arm was missing. From the shoulder down to half of his left thigh was covered in third degree burns, but the wound was cauterized to prevent further blood loss. At first, she thought he was dead, but upon hearing a single beat of his heart, as weak as it was, she rushed him out of the rubble before what was left of the structure collapsed on them.
What followed after that day was fallout from the 'high society' of Atlas barreling down upon the remaining Sterling of the family. With Argyros branded as a traitor to kin and country, most sees his son just as guilty for the acts of treason committed against Atlas. Lucky for him, the Council and General Ironwood do not see this as such, since he was a hunter being trained at the Academy for a reason and was in fact not involved with the rest of his team's defection, nor his father's betrayal. Still, he was scarred both physically and mentally from the experience and while he had his arm replaced with expensive tech, just below the Atlesian Military Prosthetic technology, he now suffers from PTSD, forced to relive the traumatic experience from time to time.