I would not paint either side of the FP. Your room as far as paint goes looks great with the light walls, darker trim & black windows. I would do inside mount roman shades on the windows (not the ones beside the FP) for some color. Get art work with more color.

MINTED.COM for art some examples

FABRICGURU.COM for roman shade fabrics

Your top picture looks like there is a decent amount of natural light coming in. The second picture looks like there is less. Light in the room is one of the elements that you need to be concerned about when chosing color. Color has a lot of impact into the atmosphere of a room. If you have a room that's usually dark, you may want to think about a lighter warm green. If your room gets a massive amount of natural light, you may think about getting a medium to light green in a cooler green. There are many different greens. Please let us know which type you were thinking of. There are minty greens, which are cool and have some blue in them. There are elemental (BM calls them) greens that are similar to a Kelly green and a forest green. Those tend to be cooler darker greens. There are gray-green, which tend to be cooler and more somber. There are earthy greens that are warm. I know you are set on green, but you way want to think about a light tan for two reasons. That's a warm color and may give you more of a cozier vibe to this room (If your room is mostly darker), and it's a color that can match more of other colors. Green may not allow you to use as many other colors in this room. The common way to pick out color is to get some paint samples from your local BM store. Get foam boards from the dollar store. Put a few colors on the boards and put on either side of the fireplace. Look at the foam board at different times of the day - night, dawn, day, dusk. Note which colors you like and which ones you don't. Paint is reletively easy to change, so don't fret if you take the plunge and you don't like it.

The room only gets sun in the morning and the yard around it has very mature tress that keep it shaded the rest of the time.

Add one big print with lots of color in it where the two prints had been. Then get a coordinating rug to go beneath the seating area. You could add a large colorful ottoman. And then add some greenery like a banana leaf or fig tree in the left corner.

Place two small consoles or even storage benches to the left and right of fireplace. Those could be white with colorful accessories/cushions on top or colorfully painted pieces. If you did consoles you could place lamps on them for some ambient lighting. It’s a beautiful room as it is so I wouldn’t “clutter” with too much color though.

If you have trees, the room will already take on a green cast. I think your room has enough going on architecturally and doesn't need an accent color/wall. I usually prefer those for walls that have no architectural features to create interest. Ae you replacing the carpet with a hard surface floor?

The floors were replaced when we moved in from dark brown carpet to light. We wanted to keep carpet for kids playing etc.

I agree with Jck, LARGE colorful art.

I also agree. use art, pillows even window treatments for your color.

Here’s an option. Oversize art on focal wall, plant and simple roman shade or roller sunscreen shades. Come in many colors but dark gray or black would add drama.

Once your big art is selected, you can determine shades and a group of coordinating pillows. Your light walls and black are stunning. I probably would have done black trim too.

i think a rug, some plants and a new coffee table will bring the space together....

thinking faux or real pink pionies,

big plant in the corner, maybe a cement planter...

and art, family pics....

IMO room already looks good and have a colors.