FYI - Instead of replying to the thread constantly you should edit your latest message and put the new update that way.
I feel this piece has a lot of potential to be so much more so I did an edit to try and push some of the elements I felt would make this piece really pop and solidify.
I've made Fiona's helmet actually act more like a helmet (it's clear and is reflecting the fire).
I've pushed the contrast of the colors via hue, saturation and value, I recommend you color pick to see what choices I've done but you should ultimately attempt to figure out my process behind what I've done instead of just copy my palette. Your original color composition is smart, it's orange and purple essentially, so push that!
I've made it so the rocks look more cubed-shaped and tried to minimize pillow-shading (which makes things look very soft, it's bad 99% of the time imo).
One of the most significant changes I did was take away the dither fire and made it more of a shape; I really don't think dithering helped there and it blended in with the rock behind fire-boy.
I hope this edit helps!