I have an older brother who is 22, older sister who is 17, younger brothers who are 12 and 9, and a younger sister who is 4.
My older brother and I used to fight like every single day. It wasn't fighting like physical fighting, I'd just bug him to death. When he was 15ish, he had a game called Diablo 2. D2 is the best online game ever, bst hack and slash game anyway. I would pester him to play, and if he never let me I would mess up his bed usually to his chasing me around the house. Now he is in college though I am so glad he still lives with us, I wouldn't be able to handle him living elsewhere. Now we don't fight much at all, I consider him like my little-ish older brother and we joke around with each other a lot. Something that is really a neat thing is that he is exactly 6 years and 362 days older than me, so usually the 7 year gap is placed on us. Another really sweet thing is Zelda: Ocarina of Time was released on both of our birthdays: mine in Japan and his in North America. We got OoT for my birthday, partially why it is my most loved game ever. The Super Smash Bros Melee event match, Seven Years, I often associate with me and my brother. : D
My older sister I really do treat more like she is my little sister – she isn't that much older than me (only like a year and a half) and most of the time when she is throwing fits of rage, I make the more sensible choices. Plus, my parents don't trust her driving by herself so I have to go with her whereever she goes, so I am sorta like a guardian for her. We got into fights, I remember I broke her Game Boy Advance and I buried it about 5 feet in our backyard (it is still there underground). We still fight, but we also are friendly in that we generally dislike the same things about people. We have a very different kinds of friends though. Where she has friends with the spontaneous group my friends are usually quiet.
My two little bros antagonize each other, so I am usually the mediator between the two but to no avail, sadly. They fight with me every single day simply because they are little and don't understand what it means to be older. I love them to death even if they leave my room in shambles, and actually whenever they are out of the house (such as going to the store) for extended periods of time I actually feel a deep sadness.
Finally my little sister is just all over the place. She starts fights with my little bros for no reason at all. She tries to help whenever she sees others helping, which in a way is really good but at the same time, she gets in the way of some jobs such as cleaning the dishes. I love her even though she annoys me at times.
I consider my older cousin who is older than me by a few months to be my twin brother for the most part. He doesn't understand things like I do, but he's okay.
I consider a girl I talk to a lot to be my little sister, she doesn't open up to me at all but the things I get about her from my friends tells me she is troubled very easily. She doesn't display much emotion and I know that those kinds of people generally are fragile people so I try not to do anything to make her cry - if she cries at all that is. If I could, I would adopt her into my family because her family is a little rough.
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As for dealing with siblings, I can suggest this: if you have older siblings (like 5 years or older), don't bug them as much as you do. You may think that you don't bug them, but you really do. Be polite, don't barge in their rooms, ask nicely fort hings but don't overask. If they say no, just take the no and be off with your business. If the difference between your siblings and you is marginal (like 2 years ish), don't fight with them over trivial things. No, they are not the devil or whatever term you apply to them, they're just confused is all. I've been there and understand it all even though I'm only 15. So yeah, love and cherish your siblings and if they bug you and you tell them no or take something from them, explain with a calm voice why they can't have/do a certain thing. :3