Eldream is a Pi'illo that is mainly purple in color. He also has bushy eyebrows and a full mustache.
Eldream isn't officially seen until Mario and Luigi reach Mushrise Park where his pillow was taken away by Brickle. Once Mario and Dreamy Luigi find Eldream, he was willing to tell them about where Princess Peach is and leaves the dream world. Back at his place, Eldream has confirmed that Peach has been taken to the depths of the dreams known as Dream's Deep. Mario, Luigi, Prince Dreambert, and Starlow then set a course of action to the Dream's Deep.
Eldream will remain at the bed where you met him for the remainder of the game. Whenever Mario and Luigi rescue a Pi'illo folk from the dream world, Eldream will give Mario and Luigi an item depending on how many they have rescued throughout the course of their adventure.