simone is young and blonde and pretty. she’s also 6’3 (literally) and mean as hell for a canadian. simone was the youngest daughter of a family that was amongst the richest in the world (we’re talking billions here) and lived an extremely privileged life style full of good schools and nice cars, where she was largely ignored and allowed to do whatever she wanted due to the fact that she already had perfect older siblings to carry on the family legacy, and she completely ran with it. she went to the university of western ontario (for the parties) and she was totally wild and completely unapologetic about it.
her family was in vancouver when the kaiju attacked as they were gearing up for her sister’s wedding and simone was supposed to be there with them except she decided to stay in ontario because she wanted to party with her friends rather than go home and have to do stuff for her sister. she was literally going to fly down the day after the attack, but vancouver airspace was put on lockdown and all she could do was sit in her apartment in ontario and watch what was happening to vancouver on the television in horror.
after the attack, her family’s company did a huge search for any surviving members but didn’t manage to find any, which meant simone was left as the sole heiress of her family’s business empire and it was at this point that she saw herself for what she really was, spoilt and horrifically selfish with no discernable skills and absolutely nothing to contribute to the world. she suddenly had all this money that she didn’t (and never had done to) deserve and all these businesses that she didn’t (and never had) know what to do with and she didn’t want them either. she resolved to do something good for once in her pathetic life and sold everything off and gave it all to the ppdc, before dropping out of uwo and joining the jaeger academy.
her time at the jaeger academy was admittedly not great. she gave up her fortune and her life style but she pretty much still had her rich girl attitude, plus she was aloof and distant and made zero effort to make friends. some asshole nicknamed her amazon barbie as a mean joke in the academy and it stuck (to the point of barbie becoming her actual call sign). most people probably think her name is actually barbie/barbara. it’s amazing that she even found someone that was drift compatible with her because she didn’t think she ever would and she was really hesitant to drift with them because she’s so deeply ashamed of the old her but her desire to pay penance for the way she was trumped her shame pretty much. they put her and her partner in one of the new mark 6 jaegers (that was probably built with her money) and her and her partner are basically a beacon of the young, glamourous new age of jaeger pilots. which probably rankles with the older more experienced rangers.
tl:dr - she’s a terrible person that’s trying to not be so much of a terrible person. by killing sea monsters with a giant robot.