Ummm don't know what happened...
Here's the rest of my post.

'the wall where the fire place is. That makes it very hard to decorate. What do you think I should do? Would it be better just to redo that half wall?'

I would leave it. I find it interesting, and it fits in with all the other angles in your house. Besides, it looks like there's a bedroom on the other side, and reworking that will probably be a fairly expensive proposition which won't gain you much.

I suggest the first order of business is to decide how you will use the room and arrange the furniture. It's possible that odd wall won't be in the way at all.

Get out the paint and paint all of the bannister rails black and paint the post white that would update the stairs to match your home