After the Swan Song quest, he will spare a player a brown apron and he will give bone seeds if the player has a pot with a pot lid. If you speak to him after you have completed the Enter the Abyss miniquest, he will let on that he is a follower of Zamorak and he will tell you about the burning of the Wizards' Tower. Given that he knows about what you did for the ZMI, he is probably a member of that organisation himself. Apparently, he had "a slight accident involving a bottle of Super-Ultra-Flora-Growth-Potion" which resulted in the creation of the Giant mole.