As the title says.

Who is the mysterious stalker? Why? What clues have we had so far that points to them?

And what are their motives?

Maybe one stalker was someone wanting to protect the FL, while the other was the one who was trying to curse them?

I wanted to create this thread so we can organize our thoughts and theories in a single place for easier access and reference.

Please mark spoilers accordingly and indicate what episode they are from so people can avoid it if they haven't watched that episode yet.