Marco and Jean.
Eren and Jean are actually friends, but pretend to hate each other as it's part of a plan for world domination.
Jean and Marco were dating.
Marco didn't die, Jean found his other-wise unknown twin brother, Marco is now living in a wood cutters cottage (with amnesia)! :D
Jean loves puppies.
Jean and Marco played the pocky game sometimes.
Marco is more of a cat person.
When Jean was a child, he lived next to Marco.