Slice of Life
Sometime after she was saved from near death by her friends, Rarity accidentally discovers she can transform in her Nightmare form at will. Terrified, she hides herself away from everyone. But when a certain dragon checks on her, it will lead to something new being born between the two.
But there is something Spike has been hiding. Sure, it was possible he would have nightmares after what transpired on the moon, but there was something else he was having nightmares about. All it will take is the comfort of a newly crowned lavender Alicorn to finally fix things. Especially when said dragon is about to hit his first growth spurt.
Meanwhile, Sweetie Belle has been having a lot of trouble of her own. She seems to not even flinch at the two bullies words, she seems to be doing worse in school, and she's even seemingly pushing others who try to help her away. And this all started after Rarity was saved. Maybe her sister is what the young unicorn needs to get her back on track.
Credit to DANMAKUMAN, Eddiedodoman, & fluffikitten, all on deviantART, for all 3 pics.