She's the person you care for with all your heart and sometimes hate passionately. She's the one you misbehave with yet the one who often keeps you in check. You've been there since her day one, and she changed your life forever. She is truly your partner in every crime, your shoulder to cry on when life is too much to handle on your own, and the very best friend you never expected to love this much. She's your little sister, and there are many reasons why she is the best thing that ever happened to you.

1. She makes you want to be a better person.

She's your baby sister, and you want her to grow up to be a genuine and well-respected person, which means you must be that person for her to look up to. She gives you a reason to be better.

2. You were her first friend, and that is a difficult bond to break.

From the day she was born, you were who she latched onto. You were her friend before she knew anyone else, and that makes your relationship unbelievably strong.

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3. She matures you.

You find yourself feeling motherly when it comes to your little sister. Your instinct will always be to protect her, often maturing you beyond your years.

4. She will always keep you young.

Although you want to be a grown-up example in her life, she will always be a reminder to have more fun and to let loose. She also has a better sense of style than you ever did at her age, so pay attention.

5. Your life-long friends have known her almost as long as you have, and they love her too.

You may have been her very first friend, but your friends fell in love with her at a young age as well. You know you've got a pretty great little sister when your friends never fail to hug her upon arrival.

6. She supports your decisions.

This does not mean she will always agree with them, but as your sister, she trusts you to do the right thing.

7. And helps you make the ones that stump you.

She may not have as much life experience as you do, but sometimes this can work to your advantage. She hasn't made as many mistakes as you have, and this can mean she's not afraid to take chances and push you to make scary decisions.

8. Distance is no match for you two.

You could go long periods of time without talking and nothing would change. You'll pick up right where you left off every time, although you prefer to stay in touch consistently.

9. You've become really good at giving advice and looking out for people.

Your little sister will come to you for advice, and you become more and more prepared to give it every time. This experience has also helped you help your friends when they need your input.

10. You will always be needed.

We all want to feel like we are a necessity to someone. We want to feel like we are improving someone's quality of life. While you may find this in other relationships over the years, your little sister will always need you, and it will always be rewarding.

11. She's a constant in your ever-changing life.

People will come and go in your life. Relationships will end and friends will fade, but your sister isn't going anywhere.

The day she was brought home, your sister changed your life dramatically. Maybe you were an only child before she came along, and she stole your thunder for a little while, but you'll forgive her for it. You'll realize that she changed your life for the better. She became your truest friend and your biggest blessing.