Heen is an odd dog who follows Sophie around. He is Madame Sulliman’s errand dog. He is introduced when Howl asks Sophie to go to the Royal Castle as "Mrs. Pendragon", while Howl follows behind disguised, and tell Madame Suliman that Howl is cowardly and of no use. As Sophie is going to the Royal Castle she is wondering what Howl disguised himself as. Right after, an old dog begins to follow her, and she thinks it is Howl. Heen is on the large side, old, and wheezes a lot, and leaves the castle with Howl, Sophie, and the Witch of the Waste. One would say he becomes their pet. http://www.onlineghibli.com/howls_castle/char.php