ELIJAH : know what to buy for each other when you go to a store alone. if you happen to stop by a grocery store without elijah, you know exactly what he wants you to get, and the same goes the other way around, he always knows what you want and or need.
KOL : feel comfortable doing anything around each other. you aren't afraid of getting naked, and he isn't afraid of being in the same room while you do so. in fact, he kind of likes it. but still, you know each other perfectly, and aren't hiding anything from each other.
JEREMY : just enter each other's houses, even if the other one isn't home. you've done it plenty of times - you go to his place, you change into comfortable clothes and then go to his bed where you take a nap and wait for him to come home.
KLAUS : do even important things for each other. he has went to where you work, and helped you out of a tough situation where you haven't been able to do it yourself. and you too, do things for him because you know how he likes them to be done.
DAMON : write text messages for each other. sometimes your hands are just too full, and you have to ask for damon to send a message to someone from your phone and he always perfectly manages to send something that sounds like you.
KAI : hurt each other's feelings. it doesn't sound so nice, but it makes you feel special when kai shamelessly lets you know what he thinks about your hairstyle, and he likes it when you laugh at his new shirt because you both know your friendship is strong enough to take it.
STEFAN : judge other people together. when you get bored, you pick a target if you're in a public place, and make fun of that person together because it's so much fun. if you don't happen to be around people, you just mock damon behind his back at home.