When I was in daycare at age four, there was a boy there that made fun of me a lot. I would cry every day when my mom dropped my sister and I off, both because I missed her when she left and because I knew what was to come that day. I think his name was Connor, and he was just your garden variety bully. But I had a secret weapon Connor never expected: my big sister.
From the early days of sending bullies running with explicit threats to kick them in the face Power Rangers style to now, having a big sister means protection. It means that when you're fifteen and a guy completely screws you over, she'll be there to put the fear of God in him about ever talking to you again. It means when a girl who doesn't like you calls you a slut, she's at the ready with a snide comment about how that girl sucks anyway. It's a subtle kind of protection: you never talk about it or acknowledge it, but it's always there.
Don't get me wrong, it's not all rainbows and sunshine. It means fighting, a lot. When you're little, the fighting will manifest itself in hair pulling and digging your nails into each others' arms as you fight over the armrest at the movie theater. In high school, you'll fight over territory: who are her friends and who are yours. Later, you'll stop fighting as much, because it's harder to fight with someone who lives 700 miles away (hanging up on someone just isn't as satisfying as storming out of their room).
In a lot of ways, no one will ever know me as well as my sister does. Time is on our side. When you spend twenty-two years knowing someone, you have all the same background: we grew up on the same shows, listened to the same music, lived in the same neighborhoods. My sister can text me the seemingly innocuous words "Did Nick know John Stamos?" and I will immediately be reduced to giggles without further explanation.
We talk the same. We make the same gestures. Back in the days of home phones, no one was ever sure which one of us they were talking to. We're each others doubles, in a way, but somehow also manage to be each other's opposites. She got all the practicality. I'm the theatrical one. She absolutely hates attention, I thrive on it. We both got the dry sense of humor and the love of learning. She got more athletic ability, I got more artistic. We like all the same things (Buffy, the White Sox, Star Trek movies) but our personalities are more puzzle pieces than mirrors. That's what sisters do. You pick up the slack where the other one needs it. She's responsible. I'm painstakingly blunt. I'm a dreamer, and she's the one who asks the tough questions. In the end, we even each other out.
So while having a sister may make you think of big concepts, like love, loyalty, or friendship, to me it's more a collection of little things. Sure, it's those big ideas too. But it's more about having someone there to speak your own weird made up language to. Or someone who will spend an entire summer with you, re-watching all seven seasons of Buffy the Vampire Slayer. Or someone who shares your love of tacos. Someone who rants about your parents with you. Someone who brought you to college parties with her, in spite of the fact that you were only sixteen and probably embarrassing. Someone who got teachers to love you by default, just because of who your big sister is. Someone who hand-decorated boy band concert t-shirts with you and went, unironically, when you were both well over the age where that kind of thing is acceptable. Someone who shares everything with you, and hardly ever complains.