'Is Mytho "Prince Sigfried" PrincessTutu A Therian' - the greatest thread in the history of forums, locked by a moderator after 12,239 pages of heated debate,
i mean listen. his most powerful form is a swan. he descends from the heavens to save rue from raven hell as a swan. he loves to do things of this sort.
also, there's something about how the heart shard of "hope" is what lets duck turn into a girl/princess tutu. and duck is... extremely (unintentionally but still) trans-metaphor-coded, in the way that her agab is duck but she is girl. she seems to really Hate being a duck (constantly describing herself as being "just a duck"), and spends most of her duck time floating sadly in water, trying to turn back into a girl, and sometimes spying on people because no one suspects a funny ducky. contrast Girl Time, where she's able to express herself much more freely, talk to her friends, dance, affect the plot, &c. she's like, a human therian, if there is such a thing.
so the heart shard of hope has the ability to transform you into an ideal/desired form. it's also, notably, the only heart shard whose form we never see - while we could assume it takes mytho's form like all the other heart shards, it could also very well be princess tutu herself, or Girl Mytho, or an entire swan. we just don't know! it's not very hard to read it as some kind of gender heart shard for swan-adjacent genders (at least, not if you're just posting for fun).
in light of this, i think it says... something, that mytho gets to transform into a swanboy prince, and subsequently a full on glowing swan that saves your life from raven hell, once he gets this heart shard back. it's not just his full heart being back, either - duck also gets to transform into a swan, or be perceived as a swan, on several occasions, so it's specifically hope shard doing it. is mytho a therian? idk, i just think there's something about him and his heart shards. he could be. it would be fun. we should let him be a swan for a while maybe