Background
Rika's parents were core-world mechanics, comfortably employed by the empire. Rather than leaving her behind to be raised by distant family, her parents took her with them throughout all of their postings in the empire. She inherited their love of mechanics and nomadic nature. She's much more comfortable around machines than people.
Her parents were killed in a skirmish between the empire and the resistance on Naboo, but she isn't certain which side fired the shot. All she knows is that she's sick of people and their squabbling and their tendency to ruin everything she loves. She'd rather stick to machines.
If she had to choose a side, she'd pick the order of the empire over the chaos of the rebellion.
Her grief forced her out into the outer rim where she hopes to establish a new life for herself and move on. However, she's also driven by her nomadic tendencies and interest in discovering/building new tech and machinery. Over time, she's started to make a name for herself as a skilled, adaptable mechanic.
Motivation