Theory: Yordles are Iverse Muses
Muses are mythological spirits that inspire artists and such; my theory is Yordles are like muses, except they are inspired by others rather than just giving inspiration directly.
- Illaoi calls them spirits, touches upon their empathy and suggest they should "inspire those that need it"
- Yordles seem to obsess and shape themselves after ideals and cultures; Poppy embodies Demacian ideals; Heimerdinger embodies Piltover ideals, for example.
That's about it. What do you think?
Demacia with her rightousness and honor
Piltover with his high intellect and ingenuity

Zaun with their questionable use of science and disregard of safety
The Glade with her crazy magic
Noxus with his lust for power and authority
Kumunge Jungle with his Scout-persona and use of poison
Freljord with his primal strength and old "age" (even if he only is a Yordle Ancestor)
Ionia with his mastery of Energy and channel of Lightning

Bandle City with their focus on modernized weaponry and skill
Shurima with his mysterious and ancient origins (maybe not a Yordle though)