Many people believe that aliens come to visit the Earth. They think of grey beings, coming here in round space vehicles that float down, where they come and greet us in an alien language. In reality, there is an alien race that recently became interested in this little planet, but they aren't interested in making direct contact, at least not yet. Instead, an alpha member of that species came to check us out, to see what made humans tick. Being severely advanced technologically, she constructed herself a human looking body, similar to an actual 21 years old girl with larger than normal breasts, modeled to give her easy access to people in order to gather data. Using a special teleporter, she materialized in a quiet part of town, then started looking.
One of the first people who saw her however took an interest in her. Possibly because he became physically attracted, the man watched as she approached another human being and act very weird. Thinking she was drunk or high, he went to try and help her. The alien saw an opportunity, and accepted the help to appear more human like in her interactions. Soon, he discovered her real identity, but stayed with her as she went from one interaction to the next, partly because of the fear of what she would do should he decide to run from her, and also because well, she's really hot.
But soon, he will discover that she isn't just here to gather verbal information. She wants to do experiments, and as she becomes more invasive with the people they meet, he has to try his best to talk her down and dissuade her from hurting people.
For this story I'm envisioning an alien being in the skin of a beautiful girl, who is incredibly powerful yet completely awkward in her interactions, with no idea of how social interactions should go, or how to be a normal human. I need someone to play a male human who would get a crush on her, and offer to help, but as the story goes on she does crazier and wilder things, and he would have to try his best to dissuade her from hurting NPCs, knowing that he can't physically overpower her. For example, she'll start by simply approaching strangers and asking weird questions, to which he could try to apologize to them, but at some point she'll want to just go in and open someone's skull to see what's inside, and he will need to do a lot of convincing to save that poor NPC's life, like remind her that cops might be near and she would expose herself, or offer to bring her to a school lab to see the skull of a dead person, etc.