Complex sentence: There, he became the friend and protector of a young girl who was also born in the Pit, after her mother was killed by the prison's inmates, where he protected her for several years until she finally escaped.
Split into simpler sentences: There, he became the friend and protector of a young girl who was also born in the Pit. After the girl's mother was killed by the prison's inmates, he protected her for several years until she finally escaped.