I would paint it white for starters. I'd also ditch the brass surround. Bigger mantel piece to give more weight up top. Don't overload the mantel with photos and other items, try to keep it minimal with a plant or a couple candle sticks and a photo frame.

Also, the curtains on that window are too short. They need to be floor length and symmetrical on both sides with the rod extending beyond. It's probably done due to the heaters, and if that's the case I would ditch them in favor of roman blinds.

Thank goodness!

OooOh ALL that potential! My mouth is drooling, just thinking of the possibilities!!

Paint the fireplace itself, black and build cabinet shelving all around. Delish!

Oooor paint the fireplace grey..like this!

Ooor do this! Build around the brick, keeping some of it exposed. And add a nice white wash to the brick. This wall color makes the fireplace visually POP!

YOU HAVE SUCH POTENTIAL IN THIS SPACE! I cannot wait to see! Have fun!

I'd wait and see what the brick looks like with the Edgecomb Grey. Then I would probably paint the mantle the darkest shade on the Edgcome strip, if it's dark enough and paint the surround black, or remove it. This is Edgecomb Gray, it's just in shadow on the right wall.
Without knowing what your budget is, I don't know how much you can alter the mantle.