>>545416525
The little I got is it seems she had to train ultra hard since childhood. I assumed part of why she is so lonely is similar to Renoa's situation of parents that wanted too much of her and she got little recognition. Though since Rin muses nobody would want someone dangerous like her, the swordsmanship became an even bigger downside for her shooing people away.
Well those are just conjectures. The sole Counseling I did of her she was suffering amnesia from the Chaos so I got little of her backstory from it.