Recap from the original:
“So, unlike her mother and other alicorns or alicorn-blooded ponies, Black Lotus has pretty much had the same appearance since she was young. She was born with mane and tail like tendrils of shadows, trails of miasma seeping from cat-like eyes, and a fanged mouth (Albeit as a foal they were far smaller). Even as a child Lotus’ looks caused her a lot of grief. Despite being the daughter of Princess Luna, she was looked down on with caution or fear by other ponies, even adults, and shunned and bullied by her peers.
One evening she came to her mother, near in tears, telling her of the names they called her like ‘Nightmare’ and ‘Demon’ and ‘Witch’ and refused to let her play with them or give her the time of day. All she wanted was to be like and play with all the other ponies. Taking her under a wing, Luna told her daughter that in time, the rest of the ponies would come to love her as Luna did, she only had to persevere, be strong, and show them what a sweet and gentle soul she really was. Someday they would realize they had nothing to fear from her.
However, as she got older, Black Lotus developed her chaotic reaction to an overload of negative emotions, and the ‘nightmare mode’ she entered from this reaction did little to alleviate other the fear of the other ponies, despite her typically pleasant demeanor.”
I headcanon now as well that the ‘nightmare’ forms are in part due to kirin ancestry in the bloodline. I won’t speak further to avoid ruining things for those not caught up.