Alright so I'm not going to bother putting in dates as this is a rough draft and seriously, keeping track of dates in Star Wars becomes a major headache really friggin fast. So let's get to it eh?
Alex Mercer was the elder child of a Galactic Senate Representative from Coruscant. His family was well off and he would have had a nice cozy life in his future had he not been taken off to the Jedi Temple for training. As an Initiate he took quickly to the physical aspects of training as well as practical application of the Force, and once he began lightsaber training he took to it quickly. On the intellectual side Alex showed an aptitude for understanding medicine and a great interest in various sciences as well as history. He also had a fair bit of cunning when it came to dealing with his fellow Initiates, politics was in his blood after all, he'd inherited an ability to tell people what they wanted to hear to influence them to do what he wanted.
During his teens he passed his trials and soon found himself training under a Master in preparation to join the Jedi Sentinels once he achieved the rank of Knight. Thanks to his balanced skills in the Force and saberplay, as well as his adaptive nature combined with a willingness to learn various technical skillsets it seemed like the right path to take. During this time he regained contact with his younger sister, Dana, who had been preparing to become a reporter to bring news to the peoples of the Galactic Republic. His sister's support gave him the ability to overcome some of the more daunting obstacles his master laid before him and also helped him to cope with stress that likely would have snapped him without her.
Towards his late teens his Master finally ran out of things to teach him and he was given the rank of Jedi Knight, with a recommendation from his Master to join the Sentinels as a Shadow. Alex followed the advice, taking to the double-bladed saber they favored more so than he had the standard style he'd originally been trained with, the weapon style seemed to come naturally to him, as did the particular work that came with the title of Shadow. He was a terror for Sith during the war, finding their hidden operations in Republic controlled space and annihilating them wherever he was sent. He was skilled at fighting multiple opponents, often times forgoing stealth just to show off, not to mention get into the best fight possible. Since he was generally sent alone on assignments, his superiors in the Jedi Order were unaware of how easy it would be to tempt his appetite for combat and knowledge.
Tempted he was, during a mission in Sith controlled space his recklessness lead to his capture. Instead of killing him the Sith lord he'd been sent to assassinate disillusioned him of the Jedi and the Republic, revealing to Alex signs of corruption and hypocrisy on every scale within their inner workings, outing the Jedi's beloved Code as a means to create emotionally dead and subservient killers, completely lacking their own independence. This coupled with his rather lax mental state from being away from home, as well as lack of support from his sister for so long served to be enough, he defected to the Sith. He began doing to the Jedi what they had originally ordered him to do to the Sith on many an occasion, kill their leaders and destroy their instructor.
Alex continued serving the Sith Empire believing them to be the real good guys till the Sacking of Coruscant, during which he participated in the siege on the Jedi Temple. many Jedi were killed by him personally, including former friends and his old Master. The looks of betrayal in their eyes, as well as disappointment in the case of his old Master, had quite an effect on him. Coupled with the fact that his fellow Sith were mindlessly slaughtering even those who tried to surrender and bombarding civilian sectors of the city planet, well, it didn't take a genius to figure out the Sith were not exactly the best guys ever. After the Sith withdrawal from Coruscant he murdered his Sith Master, perhaps a bit more slowly than needed, and made his escape to Republic space.
Alex Mercer considers both the Sith and the Jedi to be wrong in their own ways, instead opting to live by a strange combination of both Orders' codes. He's a weapon-for-higher for the most part, operating in neutral and Republic space mainly and doing his best to ruin the Empire's day at any turn, or anyone else's if the pay is right and the cause isn't too depraved. The Sith hate him for the number of important figures and installations he's taken out both as a Jedi and an independent. The Republic and Jedi Order don't trust him at all, but that doesn't stop either side from accepting his assistance in tough situations. As always both Sith and Jedi are the same in their flare for the dramatic, taking to calling Alex the Blacklight due to the color of his saber's blade. His power with the Force is impressive, he can do the lifting people and huge rocks things, fling things at people, and choke a bitch if he has to. He favors lightning though, for no other reason than he thinks it looks neat.
His choice in clothing is more than a little unusual, he keeps the hood that Jedi tend to favor but wears pants instead of a sweeping robe, as well as a jacket in the style that one would normally associate with a smuggler or a particularly over-confident bounty hunter. His allegiance is to himself, his family, and what few friends he's managed to make, he also has an unexplainable distaste for Rakghouls and the ruined world of Taris as a whole.