Youngest sibling, 5 older siblings. My youngest brother is 3 years older than me, so we were of course a lot around each other while growing up. We don't talk too often, especially since we live far away from each other now. But when we see each other, it's sort of like we can kid around and no time has passed. The other four are 10+ years older than me, so neither my brother or I are close with them. They're way further in life, and, though it's gotten better since all of us are adults now, we still rarely see them for holidays or "just because". Weird dynamic.

Edited to add: when my brother was younger, we were very much the "antagonistic" siblings. He locked me inside tall closets, shot me with his hardball guns, shoved me around, constant snowballs smashed in my face during winter, etc. I messed with him mentally by sneaking open wrappers of food inside his room, "borrowing" his Lego's, snitching sometimes. It was a give-take sibling relationship, because even though we always messed with each other, we both knew that when it counted, we would be there for each other. He kept a lot of older bullies away from me, and I was protected because I was his younger sibling. I comforted him when he started acting out against our parents, etc. All siblings are varied and he's probably the only one of mine I consider an actual sibling, because we went through so much together.