Nick

Despite her imposing build and punk aesthetic, Nick is a gentle soul.  She's shy and a bit bashful, but it comes more from an exaggerated sense of politeness than from any kind of self-doubt.  She's very curious and has passion for learning new things, but tends to absorb information in unique ways.  She has moderate inattentive ADHD.

Before the events of the story, Nick is studying botany as an undergrad.  Her goal is to run a shop selling locally grown herbs as well as rarer materials used by demon/ghost hunters and magic users.  Her family has a history of both, but she isn't very fond of danger, so she's happy running support.  Her knowledge of the supernatural is incredibly specialized- she's an expert on herbs/spell components/charms and their uses, but is pretty awful at nearly anything else.

Nick and her mother moved around a lot when she was a child, but she never really understood why.  Her mother eventually revealed that she was fleeing a cult dedicated to the fallen angel Samyaza, which she escaped from when Nick was a baby.  She was chosen to carry Samyaza's child, who he would eventually use a vessel to bring about a new era of human civilization.  Nick is that child, and the cult is now looking to reclaim her.

Eventually, the cult finds them, and Nick is possessed by Samyaza.  She disappears, but her best friend Ellie tracks her down and successfully performs an exorcism.  It succeeds, but the two of them find themselves stranded in a quaint northwestern town overrun by cultists...

Samyaza is bloodthirsty, manipulative, and hungry for power.  He uses everything at his disposal to work towards his unholy ends, but is perfectly happy causing pointless carnage instead.  Nick doesn't remember much from her time as his vessel, but what she does greatly disturbs her.

As Below is a video game concept, so here are things about her that have to do with game mechanics:
-she respects kindness and courage: making 'kind' or 'brave' remarks around her will increase her opinion of you by 1
-she dislikes rudeness: making 'mean' remarks around her will decrease her opinion of you by 1
-knowledgeable: she can identify plants and magical symbols and will give you info about them
-charmer: she'll occasionally put a protective charm around Ellie
-if her opinion of you is high enough, she might put one around you as well
-hardy: her health regens faster than average
-ace up the sleeve: immune to domination effects from succubi and incubi