(I would say Ghost Girl but don't want to come off as favouring females or smth, but the truth is that I get most of my ideas where the main character is female, and that is because I understand the female mind better than any others', being a female myself)
I had this idea while driving past a graveyard.... That is all I have to say.

-Two friends/a couple go to a graveyard at night cuz why not
-Weird things happen
-one of the two people gets ghost-y powers, such as becoming invisible/extremely hard to see
-something could happen to the other person or they become sidekick (they die, become evil, get powers but go crazy, etc.)
-this universe has no villans (that the public knows about) but there is one that has powers, but there is nothing for them to fight against
-the powers person is called something to do with sun and fire
-powers person ends up being bad (creates evil for it to destroy because there is none already (something like that)
-ghost person has to fight powers person because powers goes a little wonky (crazy)
-or it could be another sort of power, not ghost
-and yes, I know this is like a lot of other books/movies/tv shows
-uhm.... Yeah, that's all I got

The picture above is a ghost version of Livvy picrew that I made