I'm currently writing this chapter where I am supposed to explain how my character ended up the way he is at present. The reason is mainly because of insecurity towards his other sibling.

What I am aiming for is to be able to convey the character's feeling as realistic as possible so I am in need of help. My character's name is Seokhwee and he is the eldest in the family. Me being the youngest in our family doesn't really help me have a clear view of an older sibling's perspective so I want to read about what it's like to be the eldest in the family, if not, just being one of the older siblings. What does it feel like to have a younger sibling? Do you ever feel insecure/jealous? If your parents treat you and your sibling/s differently, in what way do they show it? Do your parents compare you to them openly or not? Do your parents have favorites?

Some questions, might be wrongly constructed, but I hope you could understand. English is not my native language :)
If you want to check out the story, it's and mpreg (sorry), featuring SEVENTEEN: https://www.asianfanfics.com/story/view/1228326