@Riot, what kind of spirit IS Yuumi, and what is her relation to Yordles?

We know that Yuumi isn't a true Yordle, since her form is much closer to that of a real cat, and she prefers to walk on four legs over two. However, since she seems fairly similar to Yordles otherwise; she's eccentric, is faithfully tied to her task of finding Norra, and of course, she looks like a very cute and soft animal, but with some distinctly humanoid attributes (though less than real Yordles). We also know that she was something of a cross between Norra's pet and apprentice, so she certainly seems on par with being able to live among Yordles on her own.

So is Yuumi part of a unique subset of Yordles, perhaps more distantly-removed than Fizz's subset, or is she part of a closely-related spirit species?

We don't quite know how Yordles got from Gnar's state to their current one, but it's safe to say that primitive Yordles, Gnar included, were generally far more animalistic than their current counterparts. Gnar in his Mega Gnar form walks entirely on four legs, and he even walks four-legged in his normal form on occasion too. Yordles like him also have more unkempt, wild fur, larger teeth, and big bushy tails. It's safe to say that not all primitive Yordles looked exactly like Gnar and his family, but I think we can make a good guess that they were more animalistic as well, befitting their more primal caveman-like nature.

What I'm guessing is that Yuumi is part of another "branch" of spirit from which primitive Yordles like Gnar evolved. Of course, the evolution of spirits like Yordles probably happened much differently than the evolution of the very physical animals we study in real life, but there are definitely other links between how we got from the Yordles of then to the Yordles (and related) of today. But how close are Yuumi, and perhaps other "familiars" like her, to true Yordles? What traits do they share and what traits are different? And how much about Yordles and related spirits is still yet to be revealed?