This is such a nice look at Fate's issues. She's so aware of what it means to be rejected, and to hurt the ones you love, that she's going to overcompensate. And where many of us have urges that make us feel bad or wrong for having them (justly or unjustly), she's so aware that she's not "normal", not "natural", that perfectly natural feelings and impulses are going to play into that self-doubt. It's common enough, growing up, to feel like you're some kind of freak, that nobody has ever felt the way you do, that you're broken — and Fate knows for a fact that she was manufactured, and had the person she loved most tell her to her face that she was a monster, a broken doll. That's got to multiply those feelings immensely.
She's gotten better, of course — she's incredibly strong, and Nanoha and Lindy have been very good for her — but that kind of psychic wound doesn't just go away. So it's nice to see this kind of thing touching those issues.