Taking something familiar and turning it into a fiction story can make for some interesting writing. Imagine placing Aunt Myrna in a bit of historical fiction or in a cozy mystery. She might be uptight or laidback. She might have a brilliant co-partner or a funny sidekick.
If Myrna lived in the country, have her visit the city where she’ll discover something disgusting or heinous. If she’d never stepped foot outside of her place of birth, sending her on a journey might make for a fun story.
Make your character believable with wants and goals. There must be setbacks along the way, perhaps unusual sightings, or a runaway bull.
Give her a someone with whom to share the adventure.
Write some scary parts, some funny parts, some description, some dialogue.
Have fun with this one.