I ran a 5e D&D campaign with an epic scope, Torn Reality, where the PC's are multidimensional glitches with many variants, having divergent adventures. In addition to being a good way to really delve the possibilities of the D&D multiverse and character options, its also an interesting exercise in finding the true essence of a given character. Empirically, the essence of a given character is whatever set of qualia that is consistent across all variants.

Caligord, the Bladejammer  A swashbuckling half-demon Spellblade from Wildspace.	Hie'Jac of the Old Way  A grim orc paladin dedicated to the ancient ways.
Esvel, Paragon of Ulaa  A hardened warrior blessed by the goddess Ulaa of the World of Greyhawk.	Kyoko, Creative Cozener  A mischiveous genasi arcanoklept, originally from the Feywild.