Rain, who could control water, was one of the four android creations of the Keeper.
On the Keeper's World, the Keeper was abandoned by her makers with the purpose of restoring the planet after an ancient war had devastated it. To help with this task, and to alleviate her loneliness, the Keeper fashioned four android helpers, who were nameless. Among them was an android in female form who possessed the power to manipulate rain, conjuring it at will.
During the events of the Battle of The Keeper's World, the androids chose to fight alongside Princess Leia Organa, Luke Skywalker, C-3PO, and R2-D2 in opposition to a unit of Imperial Stormtroopers. In the course of the battle, Rain unleashed a powerful deluge upon the Stormtroopers, and then, together with her fellow androids, guided the Rebels to the Keeper.
Rain presented as a human female, characterized by dark hair that reached her shoulders. Her droid nature wasn't immediately obvious, except for her photoreceptors, which resembled a yellow light emanating from within black eye sockets.
Among the Keeper's android creations, Rain spoke the least and appeared the youngest. She rarely asserted herself, opting instead to remain silent or to support the ideas of others.
Rain demonstrated complete command over her namesake element through an undefined method, capable of generating rainstorms ranging from a gentle sprinkle to a powerful torrent. She did not require any changes in the atmosphere to produce this rain, and could create it both indoors and outdoors with equal ease.