always grinning's Profile

I love the red and I love the fireplace too. What a great space! I would paint (and perhaps apply wood moldings) the top of the trapezoid area the same color as the fireplace. I think it needs to look like a chimney to make that area look" finished" to the eye. I would treat the attic area above that with a dark taupe/charcoal to make it less prominent. A good choice might be to bring in one of the darker colors of your brick wall here.
I would install white (light colored anyway, off-white, lt. grey, cream, again pick the lightest color from your brick wall) shelves on both sides of the fireplace. It would contrast the red and tie-in to the fireplace. I love your sofa, but would change the drapes to either the sofa-fireplace tones or the new bookshelf tones (off-white, light grey, cream).
If your TV is easy to view I think it would be fine where it is. I would put color-pops with mostly neutrals on the shelves and leave it very un-cluttered.
You have a great space, and tons of great advice,good luck!