R2-D2 was tired. It wasn't the temporary boredom of not having an eminent task to do. It wasn't the chilling quiet of waiting in a cockpit or other storage chaimber, just waiting to be summoned. It wasn't even the monotony of doing the same thing over and over endlessly, the life underneath their abilities some of his kind were reduced to. No, R2-D2 was just old.
Most droids had their memory wiped rather frequently. At least, most every time a droid changed owners their memories of that person were erased to avoid any conflicting loyalties or separation anxiety. His model was intended to be reset every flight, keeping secrets out of enemy hands. He, on the other hand, had not got a reset sense he had been brought to a position of honor by Queen Amidala. His odd longevity might have easily ended there, making him nothing more than a personal servant for as long as she wanted him before resuming his life, but then she ended up gifted to Anakin. The boy was great with machines, and he managed to improve R2's memory files so that he didn't go up in smoke from all of the extra data he held. He had seen so much with Anakin. He was there on every ship, he aided every battle, and he was there to see the rise of an empire. He was one of the only ones who knew about the romance between his former and current master. He was the only one that Anakin confessed his feelings to. R2 was the only one that fully understood the change happening in Anakin, but his loyalty was to his master. Even if it hadn't been, no one would ever take a droid's word on such a subject.
That changed when Darth Vador took over. R2 was passed to the family that raised his master's daughter. He had to keep quiet, and no one remembered to wipe his memory. He knew by know how to fake that he had already had his turn and when to hide. He saw how little C3PO could recall of their adventures together, and it was so lonely to be the only one who knew. No one, not even his friend knew what had happened. His friend, especially, was ignorant of the memories they shared. It was lonely, but he didn't want to forget.
The day that he went to his first master's son was a day of great danger. He had been singled out to deliver critical information, and that was dangerous for his continued knowledge. Luke himself was planning a wipe for R2, and thought nothing of it. R2 was so frightened of the prospect that he ran away to deliver his message alone, despite the nonsense about it being important that he gave C3PO. C3PO wouldn't understand. R2 didn't want to be erased, not like everyone else. When he saw Obi Wan again, it was nice to see a familiar face, even though R2 tried to hide it. The nogilesta might get him erased. Still, he had managed to complete his task, so that was something he could take pride in. It was only when he met L3-37 that R2 started to hope again. She served as autopilot for the fastest and best ship in the galaxy. All that it took, according to her, was 17 years unwiped existence with a smuggler. She had been made autopilot to get Han out of a tricky situation, but she hadn't been wiped yet. R2 hoped that he to would make a ship great. Even as he aided Luke, his master, he hoped that someday that would happen for him.
He was disappointed, however. Luke took him with him for the rebellion, becoming his friend in much the way that Anakin had. R2 hoped that this friendship would be less disappointing. Luke was innately lighter than his father had been, or so everyone who knew thought. He gladly served many years, hoping that Luke would one day give him the same honor that had been awarded to L3=37. The day that he was abandoned with Leah drowned his hopes of a meaningful life as Luke's ship. Still, a new hope was had when he was given more obscure star charts. Surly someone would see his potential now! He waited slowly losing hope, starting to rust in a corner away from the people who didn't understand. Not a single person alive knew the things that he did! He was older than most organics around by new, but he still remained patient.
His dreams seemed closer when a new generation of force sensitives were found. They were even in the sort of trouble that L3-37 had been promoted in. Still, no one even though of adding him to one of their ships, not even with all of the maps he contained. No matter what he did, people died without ever fulfilling his one wish. When would they stop fighting and give him what he wanted?