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.