To the man who marries my sister:
Hi. You probably are going to ask my parents to marry her. They'll probably say yes, as long as they really approve of you, and maybe my father will cross his arms, lean back in his chair, and try to make some joke that sounds intimidating in the process. It won't even cross your mind the others you forgot to ask. The lives you'll be entering as well as my parents. Me, and my siblings. That's fine, you don't have to necessarily ask me. You should just know what you are signing up for by marrying her.
I've never had a brother. So all those brotherly duties, yep, I expect you to start pulling your weight. I need that brother who's going to grill any guy I bring home. Who will jump in front of me in a moment notice to protect? I missed out on my parent slack of ability to produce a masculine human being, and you are going to be put in a place where I expect you to make up for it. Just saying, thought we should get that out of the way.
My family is crazy. You might already know this, considering you probably will have been around for quite sometime before you and my sister get married, but there is a whole new level of crazy you get when you actually enter the family. You are officially one of us You are officially apart of the "crazy." You get to partake in it, and when I complain about my family you are now included.
If you break her heart, you've got bigger issues than my dad. Everyone always fears the father in the family. But I guess they have never seen the damage I can do. Sure, I probably can't beat you up. I have literally no muscle whatsoever. But, I will cause hell. I will probably raise hell. I will rule hell. Yeah, sure, things don't always work out. But you better be careful about how those things just don't "work out." That's my sister. I might not always seem like I love her, but I do. And only I am allowed to fight and be mad at her. That's just how sibling privileges work.
But, most importantly, take care of her. We sisters stick together, but as we get older and go off and start to make lives for ourselves, we will lose touch. We will not get to see each other all the time, or call every day. Watch after them. They've got a bunch of weird things they each do. It's really weird, but you just get used to it. They seem really strong, but sometimes they aren't. They are going to cry a lot. Especially during their time of the month, just get her some chocolate, pet her head, she'll be fine.
We are all a very big hot mess, and it can be a lot to handle sometimes. But never give up on her because she'll be the most loyal and loving human you'll ever come across. And you don't come across people like that often.