1. He will never express any sort of affection towards you, but he'd be the first line to punch someone's lights out if they did you wrong.
2.Until you've settled into a long term relationship, he's the only guy who'll ever see you in all of your greasy-haired, menstrual-cramped glory.
3. Without a shadow of a doubt, he's pinned you down and, apologies for the crudeness that follows, passed wind on your head at least five times. There is no age limit for this kind of brotherly behaviour.
4. You've never EVER had control of the TV remote
5. When you were younger, you'd ask if you could hang out with him and his friends. Maybe your mom would force him to take you out with him. You'd feel really cool and not at all self-conscious about the fact that he never wanted you there in the first place. Think Kevin from Kevin and Perry Go Large.
6. When you were younger, you felt almost famous for the fact that his older, cooler friends knew who you were and referred to you as 'Dan's little sister.'
7. Now that you're older, he actually wants to hang out with you, and suddenly you share a lot of the same friends.
8. He was good at maths so helped you with your homework. You might have even pretended as though you were worse than he thought, so he'd almost do it for you.
9. You've fancied some of his mates, and he's fancied yours. At first, it was your turn to crush on his pals (to your prepubescent eyes they were grown men) but as you both grew older and the notion of an age gap diminished, he started to take notice of your friends. Worse still, they fancied him too. Then it got kind of awkward. And gross. Also, he forgets that he'd have had one of his friends' heads on a plate if they attempted to make a move on you, but thinks it's totally fine when the shoe's on the other foot.
10. You have no fear whatsoever when it comes to potentially squeamish/gross scenarios.
11. You cannot under any circumstances appear to get on or be actual friends in front of anyone else, though an afternoon spent watching re-runs of Fraiser in the company of your big brother isn't half bad.
12. When you've broken up with boyfriends, you've still had oversized hoodies at your disposal, in which you can wallow to your hearts content.
13. He's the one person you will be brutally honest with, and vice versa. There's no real fear that they will ever not be in your life, so any inhibitions about treading carefully are out the window. You can tear lumps out of each other with almost no consequences; it's quite liberating actually.
14. He uses the fact that he dotes on you as a means to attract potential dates. Other women think it's adorable how he looks out for his kid sister. Meanwhile, you think he's a big douche.
15. When it came to an argument, he'd always win because he was older. There was no such thing as calm, rational debate. The only real weapon in your arsenal was the ability to run crying to your parents and hope they'd take your side. Either that or you'd flip out, sneak into their room and knock all books and adornments off their shelves. Oh, that sweet satisfaction.
16. Even though you describe him as a 'tool' at the best of times, you really want him to accept and adore your other half.
17. He knows that if you're not impressed with his other half, she's toast.
18. You developed a passion for rap music long before you should ever have heard those lyrics.
19. Similarly, you were witness to one too many horror movies when you were still a kid, something that gave him great pleasure but left you scarred forever with Freddie Kruger nightmares.
20. He knows how evil you can be when you've been rubbed up the wrong way (think The Exorcist) - he's even seen you fling plates across a dinner table - but he still loves you.