Hmm. How about an Eren who HAD SOMEONE DO THAT PHANTOM THING TO HIM BEFORE *coughJeancough* and then he's in a relationship with Levi and Levi tries to have window sex and Eren freaks the fuck out and they end up skipping sex and just cuddling a whole lot while Levi reassures him that he would never hurt him like that.
levi also goes on to say that he wouldn’t be able to pull that prank, because no one’s bigger than him
and then they spend the rest of the night planning out how to prank jean back bc eren and levi as pranksters needs to be a thing y/y
mirror-wise, i think levi would break the mirror. and ooh headcanon that levi’s actually really superstitious so when he accidentally breaks the mirror during intercourse he’s liKE SHIT, SEVEN YEARS BAD LUCK