Renne was rescued from a horrific cult and inducted into a slightly less horrific secret society where she was, as a very young girl (like literally 6) raised to the rank of Enforcer, a fairly high-ranking individual who carries out orders. Her title was the Angel of Slaughter, she wielded (and continues to wield) a scythe and was very good at killing people. The Society in general is supportive of the Imperials but seeks to make the Emperor their own puppet, so generally she would have been in conflict with the Corsairs for her early life. She started drifting away from the Society around the age of 12, before being adopted by [garbled AU noises] where she's started working with the Corsairs. She's 17 now. But for about 6-7 years she was 100% a creepy anime murder child.