When Ben took on a good friend of his as a pupil, wanting to teach him in the ways of the Force, he could never have imagined the evil that he would unleash upon the galaxy.
Years before the events of A New Hope Ben was under the tutelage of a Jedi Master named Qui-Gon Jinn. As he was human, and in accordance with the rules set down by the Jedi Council, Ben wore his hair short. This was except for a long, thin braid, and a pony tail. It was at this time that he also constructed his own blue-bladed lightsaber, one that he would keep until his death at the hands of Vader. It was Qui who introduced Ben to Anakin, who was only nine years old at the time. Both could see potential in the boy. When his master passed on, Obi-Wan took on the mantle of training Anakin in the ways of the Force, mostly because he promised Qui that he would do so. Although he was apprehensive that Anakin was susceptible to the Dark Side, Ben wanted to unlock the boy's great Force talents, hoping that they would aid the galaxy.
Ben had been a general in the Clone Wars, under the command of Bail Organa of Alderaan, and had flown alongside Anakin, who was probably the greatest pilot in the galaxy. Ben himself was already a Jedi, and had been tutored by Yoda. Some may blame Ben for the events that followed, some may blame fate.
Although a strong and well-respected Jedi, Ben did not have the knowledge that Yoda did. As Anakin became more adept in the Force, he began slipping to the Dark Side. Ben was blind to this until it was too late, and Anakin had stepped over that fine line between good and evil. He was now, irrevocably, a Dark Sider. Ben begged Anakin to shun the Dark Side and return to him, but Anakin did not listen, and he was lost. In the end Ben had no choice but to face Anakin in a lightsaber duel. Although Anakin was strong in the Force, almost as strong as Ben, he lacked the experience that Ben had, and ultimately lost the fight. But instead of being killed, he fell into an open lava pit, where Ben left him for dead.
Anakin, unbeknownst to him, had children : twins Luke and Leia. Obi-Wan knew about them and knew that they had great potential in the Force. He had to hide them from Palpatine and his former pupil, who had survived the lava and become Darth Vader. Ben had relatives on Tatooine, a planet far away from the galactic core and thus far away from Palpatine. He placed Luke in the care of his brother Owen Lars, and his wife Beru. They said they would raise Luke as if they were his aunt and uncle. Leia was placed on Alderaan, in the care of Ben's life-long friend Bail Organa. She would be treated as their daughter. But one day, Ben knew, destiny would bring these two together. Meanwhile, Ben himself moved to Tatooine to become a hermit, and to watch over Luke. He knew that his time for adventures was past.
Over the years Ben became a complete recluse, shunned away by all as a crazy old hermit or a strange magician with deadly powers. He was even chased off the Lars's estate by Owen when Luke had been injured and Ben had saved him. At the time, Obi-Wan tried to give Luke Anakin's lightsaber, but Owen did not want this as he did not want Luke to follow in his father's footsteps. He told Ben never to return. But destiny would bring Luke to Ben, and it did. When Leia's ship was attacked and captured by Vader, she sent Artoo-Detoo to Obi-Wan with a message. Threepio was somehow roped into going with Artoo, and they both ended up on Tatooine. But before they could find Ben, they were captured by Jawas and sold to Luke. One night, with his restraining bolt having been taken off by Luke, Artoo trundled off in search of Ben. When Luke went after him, he was attacked by Tusken Raiders. Ben once again saved him, and this time was able to give Luke his father's lightsaber. At the same time, he began telling Luke about the ways of the Force. After hearing Leia's message, he asked Luke to go to Alderaan with him. But Luke refused, saying that Owen would never allow it. However, that all came to an end when Luke discovered that stormtroopers had killed Owen and Beru. He went with Ben to Alderaan.
Before they left, Obi-Wan had had to help Luke out of trouble at the Mos Eisley Cantina. It was there that Luke first saw the awesome power of the lightsaber, as Ben sliced off Ponda Baba's arm. At Mos Eisley Luke and Ben met Han Solo and Chewbacca, who agreed to take them to Alderaan. During the trip to Alderaan, Ben began training Luke in the ways of the Force. He taught him how to reach out with his feelings, instead of trusting his eyes. When they arrived at Alderaan, they found a meteor shower instead of a planet. Then Obi-Wan realised what had happened, for on the journey to the planet he had felt a great disturbance in the Force.
When they tractor-beamed on board the Death Star, Ben said that he would de-activate the tractor beam, and thus allowing them to escape. But while he was on board, he realised that he would have to come face-to-face with his former pupil : Darth Vader. With Leia saved and the tractor beam out of commission, Ben was left just one task. He had a vicious duel with Vader, which ended with fatal results. As they duelling, Luke saw them and walked towards them. Ben saw him and knew that he had to buy them some time to escape. If Vader saw them, it would surely be the end of the Rebellion. Obi-Wan therefore made the ultimate sacrifice. Before Luke's eyes, he lifted his lightsaber to his face and closed his eyes with the lightsaber still ignited. Vader slashed through Ben's brown cloak and the body it covered. But just the cloak and the lightsaber fell to the floor. Ben's body was gone, and his spirit had become one with the Force. Luke began to fire at everyone around him, but Ben's voice came into his head, insisting that he run.
Although Ben was dead, his spirit lived on. He helped Luke through his trench run in the Death Star, and appeared to Luke several times afterwards. On Hoth, he bade Luke to go to Dagobah and search out Yoda. When Luke received the vision of his friends on Bespin being tortured, and said that he had to go, Ben once again appeared, pleading with him not to go. He could not bear to unleash another Vader upon the galaxy. But Luke still went, knowing that Ben could not help him. Obi-Wan was unable to interfere when it came to such matters. When Yoda passed away, leaving Luke the knowledge that there was another Skywalker, Ben appeared once again and reveal the truth about Luke's heritage.
After the battle of Endor, during the celebration at the Ewok village, Ben's spirit once again visited Luke, although this time he was not alone. Yoda and Anakin were with him. Throughout the years that followed, Ben appeared less and less, leaving Luke to follow his destiny and rebuild the Jedi. He did, however, appear and tell Luke to go to Bakura and fight the Ssi-Ruuk. This warning proved to be invaluable. Luke saw Ben for what would be the last time five years later, on Coruscant. He warned Luke of danger ahead, and said that the distances between them were too great to appear again. He told Luke never to relax his guard, always be ready for the Dark Side, for that will never truly die.
As Ben left for the last time, he departed with these words : "And now, farewell. I loved you as a son, and as a student, and as a friend. Until we meet again, may the Force be with you." Luke then told himself that he was the last of the Jedi, and Ben replied : "Not the last of the old Jedi, Luke. The first of the new."
And so Ben left, never to return. But he knew that he would see Luke again, one day, when Luke made that inevitable journey; when Luke himself would become one with the Force.
