Golden Delicious (Dell), second child of Annie Smith, and the father of the Hyperborean Big Macintosh, Applejack, and Apple Bloom.
An amiable, soft-spoken fellow with a strained relationship with his family due to his rather diminutive stature and nature as a unicorn, Dell had aspirations beyond the apple farming business as a talented inventor and engineer like his paternal grandfather before him. After a fight that left him bitter towards his siblings and mother, he travelled to Manehatten in an ill-fated attempt to sell his patents and make a name for himself beyond that of the Apple family.
While unsuccessful, Dell did find one thing that was worth all the disappointment and shame; his future wife, Valencia of the Orange clan, with whom he returned to Ponyville with.
Fathering three foals with her, Valencia sadly passed away from a bad flu epidemic shortly after Apple Bloom's birth, one that also took his older sister and her family, and his youngest brother. Dell himself was killed, a year and a half later, while defending the farm against timberwolves. The story is strange on its own: timberwolves are nonviolent creatures unless their young are disturbed, and it wasn't breeding season.
But they also never found the body…
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Before anyone asks, yes, I've seen the episode with the parents — and they're still canon to the Equus (show canon) Apple family. Dell and Valencia are the Hyperborean (KirinDOS) versions.