BTS- The 8th Member (BTS FanFic)

The current 7 members are not pleased when, one day, Bang PD suddenly decides to add a new member to their group.
They feel betrayed but have to put up with it as the decision is already made.
How will the boys treat their new member?

WARNING
This is a work I wrote without putting much thought into the controversial and sensitive topics. I'm not proud of writing this, people who are easily disturbed are advised not to read this.
[This story contains very sensitive content such as: depression, anxiety, eating disorders, cutting, underage sex, poly relationships
Readers under 18 aren't advised to read this, read at your own discretion. Thank you.]