You used to be the Princess of the Piltover kingdom. But once you turned 18 and were forced to marry some prince, you had run away.
Search troops went after you but they never found you, because luckily you ran into the arms of your knight in shining armor. Her name was Violet and she was a knight for the neighbored Zaun kingdom. She found you in the forest while you were on the run with nothing but your impractical princess gown and with no survival equipment.
She took you in, she lived in a small cabin in the middle of Zaun's forest. Vi had taught you basic skills that you didn't know thanks to your pampered life in the castle. She taught you how to cook and clean, how to take care of yourself and all that stuff. She had given you a makeover, she bought you clothes so you'd blend in with normal civilians, she cut your hair shorter and taught you to love yourself without makeup. You didn't look much like the lost Princess of Piltover anymore, but obviously you couldn't change your facial features.
It's been 3 years now since Vi took you in and since you had run away. The Piltover kingdom gave up the search and declared you as dead, you were free now. Living a normal life as a normal civilian. The best part? You had fallen in love with Vi and she was in love with you. Y'all were happily together now.
You took care of Vis small cabin while Vi kept working as a knight, working long shifts.