Captain Milo Rovin is a prominent captain of the Varrock guard. He takes his job very seriously, questioning players for entering restricted areas. Players can also choose to tell him about the castle's ale delivery, in which he will direct it to the kitchen staff.
The captain can be found on the second floor of the north-west tower of the castle, at the top of a spiral staircase. But other than quests and dialogue, he has no use.