If the player passes out from low health in The Mines, Quarry Mine, or Skull Cavern, Marlon will hold lost items in an "Item Recovery Service" option in the Adventurer's Guild Menu. Players may choose to purchase one lost item, for the same price as it would be sold through the Shipping Box. Items will stay in Marlon's menu until the next time the player passes out from low health, when they will be replaced by any new items lost.
During the Egg Festival, Marlon says that despite having a bad leg he never misses a town festival. However, he is not present at the Dance of the Moonlight Jellies, nor does he have any associated dialogue.
From his dialogue at the Flower Dance, Marlon seems to have a romantic interest in Marnie. Outside of this, there are no other references to his relationships with the villagers.