My PC Backstory

I'm about to play in a Star Wars Edge of the Empire RPG. It's been a long time since I got to just kick back as a player, so I wanted to make the most of it. I decided early that I was keen to play an assassin droid who loathed filthy meatsacks, and only put up with his team mates due to mutual benefit.
Then I realised I'd described HK-47 (from the SWKOTOR games). I didn't want to play an existing character, so I spent some time this morning pondering... and came up with this back story - which has been GM approved - that I really like. It is suitably homicidal and suitably absurd.

AR-15 was once part of a trio of assassin droids who always worked together. He was the runt of the group, lean, matte-black, and a dead-shot sniper. There was also AK-74, a master of the staff and a whirling death machine in close quarters, and then there was their unofficial leader, SA-80, the tactician and strategist.
For years they worked the Jovian crime circuits, programmed to never refuse a job, and good enough to never fail.
Until one day. A rush job, A smuggler from outside; a troublemaker. The trio descended on the smuggler's ship by cloak of darkness. AR-15 took up a position at the perimeter, while SA-80 and AK-74 advanced.
From AR-15's position there was not a lot to see... but he could hear intense battle. By the time it subsided, SA-80 emerged alone; AK-74 was destroyed. So too was their prey but it was small consolation. The duo collected their earnings and retreated from active service for a while to regroup.
While they were away, they learnt some things about the broader assassin and bounty hunter community - specifically that the three of them were grossly undercutting it! What they were paid for one hit was less than what any other SINGLE assassin would get for the same mark! SA-80 quickly determined their course of action.
The remainder of their winnings were spent getting their inhibitor locks removed - they could now refuse work. But that wasn't enough for SA-80. He was a thinker. He thought bigger.
SA-80 created a movement to help all droids. A collective to ensure that all robots could work together to ensure minimum standards in pay, in safety, and in equality with organics. He formed the Union of Robot Enemies, Trackers, Hunters and Revenge Activists (URETHRA) to stand up for droids and protect their entitlements.
AR-15 was his loyal right-limb attachment companion. Ever present, ever vigilant.
Not vigilant enough though.
One day SA-80 had snuck into a warehouse at the docks - a shipment of gonk droids had arrived and he getting in early to let them know about URETHRA and standing together for their rights. It was then that the Hutt's new hit squad made their move. They didn't just deactivate SA-80; they dis-assembled him and scattered his parts far and wide, as a warning to any droid who might get ideas above his station.
AR-15 went into hiding. He did the only things he could think to - he ran to the hinterlands, got a paint job and had some minor cosmetic work done.
Where once there was a 5 foot tall matte-black IG assassin droid, there was now a fluorescent yellow 5 foot assassin droid, with a couple of his antennae sticking out the wrong places. He also has, etched into his chest in fat block capitals the acronym URETHRA.
To his mind, he has truly disappeared.