For all of the teasing, for me it was never really that you were old. It was that we were all so very young. I really do have a great deal of admiration for what you did. I am still not yet the age that you were when you started at Drew, and I know I couldn't manage to keep up with undergraduates. I barely manage to keep up with myself most days, and I don't try anything like the pace that 18-year-olds set in college. I wouldn't be able to fit in and keep up with them well enough to ever hear the age jokes.
You'll always be a little older than the rest of us, a little more sedate, a little more set in your ways. But, honestly, while you're certainly old for my age, I think you may well be young for yours, or else I'm old for mine. I imagine I'll probably always be even more sedate, set in my ways, and so on, by the time I catch up.
With age comes life experience, and I certainly relied on yours from time to time. It wasn't easy for me to learn how to be taken seriously by adults. Watching someone else who'd figured it out helped a little. Of course, you had lapses in maturity too - but that's part of the college experience.
You aren't an easy friend for me to have. You and I are so very different that it sometimes requires a great deal of tact and diplomacy even to remain civil. I know sometimes I offend you, and most likely I've hurt you at times. It goes both ways. However, when you criticize me, I try very hard not to get upset, even when I disagree. I can usually figure out the reason for what you say, and it's always worth it for me to think about it, even if I still think you're wrong afterwards. You've also come up with some amazing compliments that have confused and surprised me just as much as the criticisms. I do value your opinions, even though I don't always want to hear them.
What really matters is that when I've really needed help or support, you've been there for me. I trust and believe that you will be when and if I need it again. I try to be there for you when you need it as well. You're part of my family. I have a lot of family-by-choice, and they are just as important to me as my family-by-blood. I'm not even sure I actively chose you as my big brother. That's just who you are.
Then again, that also means I feel fully entitled to go all out for your birthday in a couple of years, especially if you make a fuss over mine. After all, it's a little sister's right to be an annoying pest, isn't it?