In two weeks you turn four and a half. I'm rushing to write this letter to you, as late as it is, so that I can write you a half birthday letter on time. Here goes.

You are now a big sister. Insert eyeroll here. No, but really. You are now a big sister. You say it is so.

My entire pregnancy with Arden you insisted that you were NOT A BIG SISTER in that big, insistent way that you do. You were adamant. You were a baby. And that was fair. No one in this family ever asked anything of you as a big sister. We were fully supportive of your babydom, and we let you keep it as long as you needed. And, nearly two years later, you are now ready to be a big sister.

And what a big sister you are! When the two of you get along it is like rainbows and unicorns. It is literally the most beautiful thing anyone has ever seen.

And then the two of you are clawing each other's eyeballs out, and Arden has a fistful of your fine, blonde hair, and you're growling and howling like a wounded 300 pound lion and it's so, so ugly.

Ying and yang, eh? I'll take it. Watching to two of you work it out over the last two years has been a process, but an honor to witness. You two will be quite the duo, I'm sure of it. You introduce her to strangers and defend her on the playground. She can hold her own, but having a big sister in her corner is probably what gives her the balls to do so. I don't doubt you will hold her hand and guide her, as only a big sister can, and she'll pull you off the path and show you things you never knew, like only a little sister can.

Enjoy your sisterhood, my dear. It's like nothing else.

Happy Fifty Third Monthday.