Chartreuse

She had no real name. She was hardly a real person. She was nothing but a collection of wild magic acting as one, intrigued by humanity and delighted in learning how to communicate with the funny little creatures that always have to stay in one piece. She learned how to seep into their dreams, scaring nearly everyone she ever spoke to. Deciding this was fun, she enjoyed provoking fear by purposefully giving people nightmares. It's not that she was malicious, morality is just not a concept to ambient magic.

Eventually, she found an interest in an old professor, one who'd spent his entire life studying the very magic she was made up of, and made this lonely old man her next target. He wasn't intimidated by her much at all and instead, she ended up interested in getting to know this odd human. In turned, he spent his time outside of teaching to research with her a way to make her form in the waking world solid as well. I'm sure you can figure out what happens when an ancient being and a kind old professor spent years together researching and learning to understand their very different existences...but that's a story for another day.