Discord was created when Puddinghead sneezed behind Starswirl the Bearded while they were trotting along at the zoo.
Celestia and Luna were the former Element Bearers, back then, being 6 separate ponies. Puddinghead sneezed while they fired their Friendship Harmony Laser Ultimate Rainbow Beam (FHLURB) at Discord.
Those first weeks... were awkward...
The "Royal We" Really is the "Royal We"!