To start with, here is my backstory for the 13 years old urchin girl Myrtil is in New Babbage :
Myrtil is an orphan. She lost her parents and brother when she was five years old.
Her father was an adventurous airship captain and her mother a biologist and inventor. They died in a storm with their son while they were flying above the sea.
She had been left to a neighbour and as she had no other known family left and that her parents were not really rich, she was sent to the orphanage.
Life wasn't very happy at the orphanage and Myrtil grew feeling like in prison. Sociable, she made some friends at the orphanage, but when she turned 10, she decided she could no longer live there and escaped the orphanage.
She then found herself wandering in the streets of New Babbage and soon met a bunch of other urchins who brought her to the hideout under the attic of an old abandoned Imperial theatre where they lived.