When we think about what lead to a character's development or even our own development, I'm not sure if "sibling relationship" always appears on the list. But don't our brothers and sisters have a huge impact on how we see ourselves and the world? I remember reading somewhere that the biggest influence on who we become is not our parents or our friends, but our siblings, and I think there's a lot of truth to that. I have three sisters and a brother who passed away when I was two. If one of them had never existed, I would be a completely different person.
For this prompt, summarize or write a scene where we see how the presence or lack of sibling(s) affects you or your character. How does the relationship affect the choices your character makes, who she becomes, or how he sees himself in the world? What does this person believe about their capabilities or potential because of their sibling? What do they believe they deserve and can achieve? How did this relationship influence other relationships in your character's life?
This should be an interesting one. Let me know how you approached this prompt and how it went, but please, don't send me therapy bills if it opens any flood gates!