The story starts when Twilight asks Celestia a simple question: "I was wondering if you and Luna were born alicorns, and if you weren't, well, what species were you before your ascension?" As it turns out, Celestia and Luna were not always alicorn. They were in fact born mules.
Delusions has a premise that would usually be written as a Crack Fic, however it is completely serious in its narrative. It tells the origin of how Celestia and Luna became the ponies they are.
Delusions provides examples of:
- Child Soldiers: As teenagers Celestia and Luna worked with rebels against Discord's reign.
- Half-Breed Discrimination: Pony/donkey relationships were looked down upon when Celestia and Luna were young. Luna and Celestia faced a lot of discrimination for being mules. Even in modern Equestria there's still a stigma against mixed relationships and their offspring.
- Heroic Albino: Celestia was born an albino, explaining her pink eyes and white pelt.
- Locked into Strangeness: Celestia was born with a white mane but gained her multicolored, ethereal mane upon ascension.
- Meaningful Name:
- Celestia's parents named her that because her all-white colouring made her look angelic.
- Luna was originally named "Philomena". She was named for her stocky, sturdy form.
- Meaningful Rename: Philomena changed her name to "Luna" upon ascension.
- Mixed Ancestry: Celestia and Luna have an Earth pony mother and a donkey father.
- Really 700 Years Old: In canon, it's vague how old Celestia and Luna are aside from the fact they're over a thousand. In Delusions it's mentioned that they're "several thousand years old".