I would update your lighting and make a feature of both with downlights and modern artwork on the walls. Once painted, it's hard to go back! It would then match your windows too.

PAINT!!! Pant both walls in a white or light grey. The room will instantly look larger and light filled. Example below of a white wash! if you want to keep some of the character.

i painted my cedar walled lounge room . you can find the after and before pics under ”ugly brick fireplace” and is a quick makeover idea. you could find someone to render the brick wall like i did with my fireplace , if you want to lighten up the brick wall. hope it all turns out well for you.