Sis,

There are friends. Then, there are best friends.

According to "Grey's Anatomy's" Meredith Grey and Cristina Yang, they're your person. You're so much more to me than any of those titles can express.

As I've matured throughout the years, I've come to the conclusion that good friends with good hearts serve an incredibly important purpose in our lives, going above and beyond what we give them credit and appreciation for.

The family we choose. You're one of those.

The day we met, I knew that you were going to play an important role in my life. What I had no idea of was that you would join the cast of my life with a starring role.

First, I need to say thank you. Thank you for always coming to my locker to check in before class during high school. Thank you for letting me control the music on road trips. Thank you for sharing your family with me, and addressing my family as if you were born into it.

Thank you for patiently listening to the physical embodiment of a broken record when I complain about the same boy I've loved since senior year. Thank you for tagging along on every doctor's appointment, grocery run, and trip to the post office, just because you know that I hate doing things alone.

Thank you for not thinking twice before dialing when I text you, “Please call me." Thank you for never saying no to a coffee date. Thank you for never giving up on me. Thank you for being my better half.

We don't share the same genetic makeup, but after all the sleepovers, heart-to-heart conversations, shopping until our bank accounts cry, and swapping clothes so often that we don't know what belongs to whom, how could I not consider you family? We have shared some of my fondest memories together, and I wouldn't want them to feature anyone but you.

You've been with me on my best days and loved me on my worst. You know how to make me laugh when all I want to do is crawl into a hole and die.

Picturing sitting in my car with you in the passenger seat makes me long for summer, where we spend three months together doing all of our favorite things. You've seen me naked, done my makeup, and warned me before making a poor decision. Being away from you for extended periods of time makes me feel incomplete.

You are a piece of me that I am not quite whole without. You taught me that blood doesn't make a family, love does.

You know me better than I know myself, which is both amazing and terrifying. You make me realize I'm enough for this world, and that means more to me than I know how to express in the limited words that make up the English language.

You remind me that I am more than my mistakes, and you keep me grounded when I spiral out of control. You've helped me carry my burdens along with your own, even when the universe comes down on you full force, way harder than you deserve.

You're the one I come to for the truth if I think my new dress makes me look fat, and I know you'll be honest. I trust you with my whole heart. You know the gory details about every boy I've ever crushed on, every professor who was an absolute jerk, and every fight I've had with my mom.

I wouldn't make it in this life without someone who already understands and listens to every thought going through my head and each thing I seriously over think, even when you know, though you don't say, it won't matter in a week.

With all these affectionate things being said, don't forget our fights. The few we've had were very real. We still don't see eye-to-eye on some events of the past, but I never told my mom about it because there was no need to make her choose a side between me and her “second daughter."

We have learned to move forward, because the love we have for each other overwhelmingly outweighs any disagreement we've had, and always will.

Through all the tears and laughs, I don't think that anything the world has to offer could seriously come between us. You go to a different school than me now, and college has rudely gotten in the way of our routine of spending every waking moment together.

Since we met, we've grown separately without growing apart. Neither of us are the same person we used to be all those years ago. Even so, we've pushed each other to our limits and you've given me the courage to keep going and do things that make me happy.

We lean on each other when it's been a bad day and all we want to do is to snuggle and indulge in whichever show the other is currently watching unceasingly and unabashedly for comfort (it's the little things). Having you as my co-pilot on this crazy ride called life has been frustrating, exciting, slightly concerning, absolutely insane, and something I don't know how I would live without, and I don't intend to find out.

I'll conclude this letter with a quote from every basic, white girl's favorite musical, “I don't know if I've been changed for the better, but because I knew you, I have been changed for good."

Love you forever,

Your sis