Tegan is the one who always gets you a gift for holidays when you didn't think you were exchanging gifts.
Sara is the one who buys colored glass bottles at yard sales.
Tegan is the one who told you about The Gallery of Regrettable Food.
Sara is the one who has been making the same scarf for three years, and it's much wider at the top.
Tegan is the one who if the two of you were staying in a hotel together and you realized there was something wrong with the room but didn't really want to make a big deal out of it with the staff, because you're not that kind of person, she'd go down and get the room switched but in such a way that didn't put anyone out or make anybody uncomfortable.
Sara is the one who digs at her cuticles but has perfect short-clipped nails, filed to be square-ish.
...let's agree they both have short nails.
Tegan is the one who would know the non-emergency line for the police in your area so that if you saw an old man walking around the neighborhood looking lost and confused and couldn't answer any of your questions, she'd be able to summon help without tying up the 911 lines.
Sara is the one who always knows exactly which episode of Golden Girls you are thinking of, and who the guest star was.
Tegan is the one who correctly guesses the murderer like, four minutes into a mystery, even if she hasn't seen it before. Not just the easy ones, like Law & Order. Poirot and Foyle's War too.
Sara is the one who's always up for being dragged to those small local military history museums when you're on vacation, even when it's just a cannon in a field with an illegible plaque next to it.
Tegan is the one who has a flashlight and jumper cables in her car. You keep saying you'll get to it ("I know, I know, I should really get one, I know I'll need something like that eventually") until one day you open your trunk and find that she's quietly placed an emergency kit there for you.
Sara is the one who stole a restaurant chalkboard for you after the owner asked the two of you to stop making out.
Tegan is the one who orders coffee-table art books she'll never read or even open most of the time. Your apartment together is covered in precariously balanced book piles, half of which are still in their Amazon boxes. "What do you need all this for," you ask her, half exasperated, half laughing. "I know," she says smiling. "I knoooow."
Sara is the one who has a godmother who has given her a blank journal and a horse calendar every Christmas since she was six. She always messes up and tears out blank pages and then tosses them, but genuinely appreciates the gesture all the same.