Maybe something like this? It could give it some symmetry.

If you really need curtains, you should probably do a roman shade on pulleys that stacks along the bottom of the long side of the window when not in use. You will need to get two wires to guide the shade up and hooks to hold the cords. You could pull it up the long way, but the eye that holds the wire/cord guides is not going to be at the top of your window.

The simplest version is to put eye screws in the four corners, tie cords from top to bottom, these cords would go through rings on the back of your shades. Also through the rings would be a cord on each side, one end attached to a corner of the shade, the other would go through the eye screw at the top, you'd pull this cord to close the shades (up would be closed) and fasten it to a hook on the side of the window (the hook or cleat placement can be anywhere convenient). You could add pulleys, but you don't have much space.

You don't really need much fabric, so get something pretty, be sure to line it if you need it. If you do home sewing, you can buy tape with the rings pre-sewn, so all you need it to use your machine to put the tape on the back of the shades.

That said, this is a tough place to put shades in and if you don't really need them, don't bother.

I believe a top down, bottom up cellular shade should work in your situation.

yes the skylight option would work well

A 'coffin', 'witch' or 'Vermont' window as these are called, can be a bit tricky!

We are located in Vermont, so we come across them often. We treat them just as skylight. Cellular shades can be made with light-filtering fabric. (as seen here)

Cellular shades can also be made in room-darkening fabric.

You can have the shade manual or motorized, whatever works for you.

Shutters are a great option as well.

It all depends how sensitive you are to light.

a "witch window!" or Vermont window. :) I am trying to figure out how I want (if I want) to cover ours. Getting some good ideas. Thank you!