It was their fateful trip on the Tantive IV that truly brought them together. While 3PO was being transported to its newest master, Captain Antilles, R2 was being programmed to seek out Obi-Wan Kenobi and deliver the secret plans stored in its memory. The astromech droid was to be jettisoned to Tatooine alone in search of the Jedi Knight. Unfortunately, Tantive IV was overtaken by a Star Destroyer minutes before the droid was to leave. There was just enough time for Princess Leia to record a final plea before sending it off. What was not in the plan was to have 3PO tagging along, bailing with R2 to escape being melted down by the Empire.

Very soon after landing, the two were captured by Jawas and sold on auction. Fortunately for both of them, they were purchased by Owen Lars and placed in the care of Luke Skywalker. They couldn't have asked for a better guardian. R2 didn't recognize Luke for who he was and had no way of knowing the role Luke would eventually play in the Battle of Yavin. It continued to seek out Obi-Wan on its own, prompting Luke to go after it, and eventually, student and master Jedi were introduced.

The droids have remained with Luke ever since and their skills are put to use for the Alliance on a daily basis. Threepio's protocol and linguistic talents are used to monitor Imperial security bands and translate intercepted codes, while Artoo's mechanical programming skills are put to use in the rear pod of Luke's X-wing. The two are "spiritually" inseparable, despite their constant bickering, and when separated for long periods, actually begin to "miss" each other.

C-3PO is a protocol droid with specialized programming in droid/human relations and language translation and interpretation. He is bipedal, with a gold-colored body. Among Threepio's standard equipment are visual, auditory, olfactory, and sensory receptors, a broadband antenna for receiving droid transmissions, and a speech vocabulator. He is fluent in over six million galactic languages.

Design specifications for this model droid call for limited creativity circuits to keep embellishment to a minimum. Over the long period since C-3PO's last memory wipe (if he ever even had one), he has apparently developed a talent for telling stories, as evidenced by his dramatic re-creation of the events of the galactic civil war for the Ewoks of Endor's forest moon.

C-3PO claimed that he and his counterpart, R2-D2, were the property of Captain Antilles when they first met Luke Skywalker, though the protocol droid readily accepted Luke as his new master. He even claimed not to have ever heard of Princess Leia, though this seems unlikely. Since meeting up with Luke, C-3PO has shared many adventures with the Heroes of Yavin. He tends to stay close to Princess Leia when Luke is away.

The astromech droid R2-D2 (or Artoo-Detoo) hooked up with Luke Skywalker at the beginning of the events that led to the Battle of Yavin and has been at his side ever since. Like other astromech droids, R2-D2 is a starship utility droid. His domed head can rotate a full three hundred and sixty degrees, and his short, squat, cylindrical body is full of instruments, sensors, and devices designed to help him perform his primary functions.

R2-D2 stands upright on two legs that end in treaded rollers. A third leg drops from a compartment in his lower body to provide him with added stability when moving across irregular terrain.

Artoo-Detoo and his counterpart, See-Threepio (C-3PO), were aboard Princess Leia's consular ship when it was overtaken and boarded by Imperial forces. The Princess placed the technical readouts for the Death Star in Artoo's memory banks, then ordered the little droid to find Obi-Wan Kenobi. Since that time, Artoo has served as Luke's companion and aide, assisting from his socket in Luke's X-wing, accompanying him to Dagobah, and helping to save the day on Endor's forest moon. Artoo understands Basic, but communicates in his own expressive language of beeps and whistles, which Threepio must often translate for their human (and Wookiee) companions.