system
Given the following post, respond as if you're commenting on Reddit:
human
[Tolkien] Did Melkor ever had a "non-evil" sphere of influence, like the Other Valar did?
gpt
There's very little mentioned outside of his inclination towards extreme heat and cold - but we can make an educated guess by process of elimination.

There are three notable "elemental" Vala - that is, ones who primarily identify with certain areas or elements. 

Manwë - the sky, wind, birds, air
 
Ulmo - the sea, all waters, rivers and streams

Aule - the earth, minerals, jewelry, craft

So we have one notable missing classical element, obviously fire. Probably that would have been more like "natural forces", from volcanism, to blizzards, to earthquakes, as well as temperatures. Maybe he could've been an Apollo like sun deity, but travelling around Middle-Earth bringing light and heat to Yavanna's plants and wildlife.

We have the example of his work combining with that of the other Valar to make good things that he didn't intend - his extreme cold combined with Ulmo's waters created snow. In the end, like Eru states in the Ainulindale, everything Melkor would be turned into a new and sudden good thing by Eru, no matter what Melkor wanted in the end.