I wanted to just open a poll on the trope of an older person becoming younger by means of reincarnating, transmigrating and regressing, or possession and it's subversion, a younger person becoming older by means of transforming, etc. I want main character's past to play a significant role in how they are, and in their relationships. My main character was a teen soldier who due to an event, possesses the body of someone older than her, going from a apocalypse world to a peaceful one. (Both modern setting.) While I still don't know if I want my character to mature or have all the baggage that comes from the premise, I want ideas on the conflicts that my main character could encounter.
Great idea! You could explore conflicts like: feeling lost living someone else's life, difficulty fitting in due to war, PTSD, or internal conflict between age and appearance. These would add depth to the character and plot.
If you haven't, read Howl's Moving Castle. Both because it's a great book so everyone should read it and while the movie is adorable it misses a lot of the nuisances about the transformation from a young girl to an old woman.
I just got to see this reply. Could I ask how you managed to read it? I looked to pdf's and physical copies, asking the obvious but is the author Diana Wynne?
Yep, diana wynne jones Most libraries carry it, depending on your area I got it from my middle school's library personally