Recently I have made small deisgns and ideas for elementals that primarily reside within the AU. Pretty much same concept of elementals in most fantasy worlds, creatures made purely of the specific element it is.
The elementals follow the same sort of rules, along side a core of condensed elemental energy acting as a "soul". Most that are around are small, being more small-medium animal sized depending on age.
What gets interesting is how this factors into the Guardians. It's unclear when this phenomenon occured, but after a while Guardians tended to have more elemental based bodies. Their element being highly involved during development, said to be caused by the true nature of their power.
This allows a Guardian more stability when using their element, more leniency to their physical form compared to a normal human or monster. Effectively a hybrid in a sense, still giving some limitations. It also influences appearance as well, blood for example, is purely elemental magic.
This being noticeable in Onyx and Star's designs, being twins despite having wildly different apperances. Will as well help actually design the others as well.
Alas that will be all for today, with possible sketches in the forecast :3