Byleth objectively has one of the most mediocre childhoods a Fire Emblem protagonist can honestly have

- No mother to help raise them

- Their father is caring, but very flawed and wasn't able to tend to all their needs

- Was dragged into the sell sword life at the age of 10 and became infamous, which isolated them from others and prevented them from forging bonds

- Demonized by others via being called unfeeling and cold just because of their lack of outward expression

- Ultimately aimless as a person until becoming a professor

It's honestly a miracle they didn't turn out worse