Arf, a K-9 series droid belonging to Havet Storm, was a nickname. Havet Storm received Arf, who was essentially a plaything, from his grandfather, Morvet Storm. A secret audio message was recorded by the Jedi Morvet for his grandson, using the droid; it spoke of Havet's latent Jedi abilities and cautioned him against revealing them.
Inside the K-9 unit, Morvet Storm also concealed a lightsaber. This remained hidden until Havet Storm took possession of the droid and triggered Morvet's protected message. He did this by interacting with a DNA sample reader located on the droid's exterior.
Havet Storm found Arf to be incredibly useful in several situations. He carried the droid with him constantly, concealed in a sizable pocket within his heavy coat. The droid displayed unwavering loyalty, responding solely to its master's commands, and the two developed a strong connection.