So I've been sitting on this one for a while, having completed it shortly after the one of her as a child. I'd originally intended to post it with a bit of character exploration. However, the writing didn't seem to do the concept justice.

She is intended to be to Discord as Luna is to Celestia and as the CMCs are to the Mane 6. That is, Discord and Celestia and Twilight and her friends are focused predominantly on what goes on in the world outside of themselves. Celestia keeps the government and day-to-day affairs of Equestria mostly in order. The Mane 6 fight monsters and solve friendship problems that affect the world around them. Discord is, of course, able to turn the physical world on its head.

Luna and the CMCs, by contrast, are more about the world that exists inside of themselves. Luna is the guardian of the dreams of her subjects, and when those get out of hand there is (with the exception of the Tantabus) not a concrete manifestation of the problem. In a similar fashion, the CMCs deal with individual identity and self expression. While they can cross over and deal with outer world issues, and vice versa - think Discord and his inversion of the virtues of the Mane 6 - it is not necessarily what they are most proficient in. Discord seems to have much more fun with chocolate rain and cotton candy clouds and the like than manipulating the identities of ponies.

Tapsalteerie was intended to fill what I perceive as a gap. While she doesn't intend to be malicious, like Discord she enjoys a little chaos and given her focus on the inner world that manifests itself much more as casting doubt on established ideas or modes of thinking, or the way in which individuals define themselves.

Her component animals tend more to the aquatic or semi-aquatic since to me that fit her theme better. She has a shark tail, a skink body, tiger and polar bear legs, otter and crocodile arms, owl and hummingbird wings, a draconic head and neck with a sea dragon mane and angler fish bulb.