Angels have always been around. Just not in the way you'd expect. They're born from starlight and human's pure intentions. That, is how Olivia Wilde was born, like those before her. However, she wasn't like the rest of her kind. She admired humanity and didn't want to distance herself from those she was made to protect. After all, how could she protect those she didn't understand? So she spent several hundred years just watching humanity grow and flourish. Occasionally she'd sneak down help those with a pure heart.
Once, there was a woman who wanted a child. Olivia knew she was pure and she had almost given up, so she helped her. This, of course, didn't go down well with the rest of the Angels. They were supposed to guard, not interact. Olivia disagreed. Which, promptly lead to her exile. Olivia didn't care. So thus, she spent the next century living among men and silently helping their lives be slightly better.
She has only used her power twice after she was banished. The first time, Olivia came across a land in very long drought. People were dying from hunger and dehydration. So, when she heard their hearts cry out for water, she nudged the clouds to darken and let their water go. The second time, she came across a man who was a werewolf. He wanted nothing more then to be a regular human, since his heart was pure she helped him.
On one of her many wanderings of the world, she encountered a hidden school in Austria. A place where many learned and grew in a safe enviorment. Naturally, she entered and found many of the deziens of Earth. At first, she was just a student. She wandered the halls constantly and continued her self-appointed task of helping each and every single one silently.
That, is how she became a professor. She didn't want to leave a perfect place to brighten somebody's already dull life. It wasn't easy being different and she knew that for a fact.