This story may fall apart because of the encounter with Pixie cut.
I’ll explain it anyway.
For Limestone it is someone who most of the time is angry however as she admits it is due to a lack of love and Zephyr only asks to love someone after his disillusion with rainbow dash.
For Zephyr Breeze he is unbearable but that said it is due first of all to a lack of rigour that Limestone is close to imposed on him.
so in conclusion they are complementary and so they can erase their defect.