An extremely worried entity who controls fate, not just in one dimension but in all of them.

The entity gets its power from the space located in between dimensions (which is a lot, so they are VERY POWERFUL)

Spaced is like inverted version of the night sky, but the only reason anyone knows that is because someone once made it to her Inbetween Place, and she helped them make it out alive, but no one believed the person on what he saw and told him he was crazy.

Spaced is the only other entity powerful enough to stop Flash, but Flash actually does good stuff sometimes, so Spaced can't just wipe Flash out or else there will be consequences. (of the unspecified region) Spaced also doesn't interfere with what Flash is doing too often, as Spaced can just fix whatever Flash breaks.

The Inbetween Place is a big open black space (with no perceivable end) and holds many different tablet shaped glass things that show into worlds and allow Spaced to see what is going on and what she needs to fix or change.

Spaced and Flash haven't actually met in person, and probably never will.

(I will probably elaborate more later)