Or as I alternatively named them in a bout of genius at 3 in the morning:
"OTP asks"

*ahem*

Which one hogs the blanket?
Definitely Armin--

Which one cuts the other's hair?
Armin desperately asks Eren to cut his hair because it gets in the way a lot but Eren absolutely refuses because Armin's hair is beautiful and he loves it so much

Which one makes coffee for the other in the morning?
Eren, most definitely,,, Armin wakes up really groggy and basically still asleep while Eren is a real early bird so he has to wake Armin up with some good ol' caffeine

Which one picks up the pizza?
They both have no problem with going out and picking up pizza but it's mostly Eren because Armin is either too engrossed in a book to pay attention or he's half asleep on the couch so Eren generously goes out in his stead

Which one likes their music on full volume?
Armin, Eren doesn't mind much because they have pretty similar music tastes, though Eren's tastes include just a bit more K-pop, while Armin's not too keen on K-pop, he specifically really likes Panic! At The Disco; they both really love the oldies, not really "oldies" but more like things from the before 2011. But you know what they BOTH really like? MUSICALS LIKE DONT EVEN GET ME STARTED--

Which one is ticklish?
Both, but Armin would much rather respect Eren's ticklishness, while Eren tickles him at pretty much any chance he gets, like if Armin's just quietly reading a book on the couch Eren is on that so quick

Which one sings and which one plays the music?
Eren loves Armin's singing voice so he'll often put on a song that Armin can't resist singing to and even if Armin is purposely singing badly he just sits back and admires him but when Armin puts on any pop music EREN TURNS IT INTO A LITERAL CONCERT IT'S NOT EVEN FUNNY LIKE HE SETS UP A WHOLE DANCE ROUTINE ON THE SPOT AND EVERYTHING

Which one proposes?
Eren. Eren. Eren. Eren. E R E N.

Which one cries during Disney movies?
Oooh my god don't even get Eren started on Disney movies he will start bawling on the spot

Who does the silly hands-over-the-eyes "guess who" thing?
Eren does it all the time because he's just a huge dork and Armin never gets tired of it

Who puts their cold hands/feet on the other?
Armin does it just to make Eren glare at him in the cute way he does

Who has that embarrassing reality TV marathon?
Eren lives for reality TV so really there's nothing embarrassing about it he honestly embraces it

Who laughs more during the do?
EREN EREN EREN EREN EREN HE JUST GIGGLES LIKE AN ADORABLE MANIAC AND IT'S AMAZING

Who is the little spoon?
*inhale--*
Armiiiiiiiin,,,,

Who asks weird questions in the middle of the night?
Both, Armin because he's probably sleeptalking and Eren because they're pulling an all-nighter and they're really sleep deprived and delusional--

Who's more likely to cry over a sad book or movie?
Eren cries over sad movies, Armin cries intensely over books, even if they're not sad books he'll just cry because it's perfect and he loves it so much and then Eren has to comfort his overwhelming happy tears

Who talks smack during video games?
ARMIN WILL MURDER YOU WITH HIS WORDS IF YOU PLAY A VIDEO GAME WITH HIM HE WILL DEMOLISH YOU AND YOU WILL CRY

Who sings along to the radio?
They both do, lovely duets lemme tell ya 👐

Who would accidentally set the kitchen on fire while cooking?
Definitely Armin, he cannot cook at all,,,

Who would throw the other into the pool/ocean?
Ah Eren of course; if he sees that Armin isn't enjoying himself or even worse, falling asleep, he'll immediately pick up the boy and just whOOSH S P L A S H

Who shops for groceries?
They go together <3

Who kills the spiders?
Eren is absolutely terrified of spiders so he always forces Armin to kill them--