One fallacy of character design is having bodies that always match personality types; the body is a visual metaphor for the character as a whole. This makes for easy visual cues and recognizability, so it’s a useful tool, but it’s important to remember that it IS a fallacy in most cases, and playing with that tension can be very effective (and it’s also probably necessary for realism).
For Ainur characters though, their bodies ARE a visual metaphor for their personalities. Their bodies were made expressly to suit their needs and desires; they were their own designers, their flesh is an extension of their thoughts and feelings. Except for Melkor’s.
Melkor is the only one stuck in his body; and for a spirit that mercurial and prone to extremities, there could be nothing more demoralizing.
I can’t tell you how therapeutic it is to have a muse who is at least as heartbroken as I am about the fixed nature of their body, with its permanent maladies and limitations; who, even if they had a body that was perfect, would not be content because it was only one, a singular facet being forced to represent something manifold. Am I projecting a bit much? Probably. But there was a reason I was drawn so hard to this character and why they have stuck with me this long. There are many reasons why I like Melkor and relate to him, but this is definitely one.