Whenever I hear 'Into someone elses body', first thing that come to my is the body dysmorphia that I would be swelled into. Suggested but not excluded to: Gender Dysphoria Societal Issues Disabled body Lack of Adaptation Identity Confusion Unhappy Ending Loss of Body Rape(Should be portrayed as bad; No Rape Victim to Lover trope) Overall I just need the person to suffer. Just a Physiological breakdown if you will.
It honestly would depend on the type of transfer I think. Someone transferred as a baby, (without remembering everything all at once) would be able to adjust. I prefer reincarnation stories that are more realistic for this reason. That is, being born into the world, and only recovering vague memories of your life before once you become a little older. The suffering you would get for adjustment would be at minimum.
Ending Maker (body with illness) Holy Emperor’s Grandson is a Necromancer (body got hanged previously) Soul of Negary (body died cuz couldn't adapt) The Editor Is the Novel’s Extra (sickly body) How to Live as the Enemy Prince (previously poisoned was it? sickly anyways) Trash of the Count’s Family (weak body always coughing up blood) The Strategy to Become Good at Magic (age regression after transmigration)
I've transmigrated Into This Movie Before QT about a actress who improves her acting ability by being drawn into the setting of a (tragic) movie but at the cost of her sanity Whenever she comes back to reality, she has to live with the emotional scars of her previous experience The Yandere Came During the Night FL transmigrates into body of female character that recently lost feelings in her legs Not exactly body dysmorphia since she was bound to a wheelchair her whole life/for a long time already
Power up artist yang has body dysmorphia in layer chapters and finds out about the person who used to have the body. It's a good read. I'm not sure about suffering severely though