
If Anakin is the embodiment of the Dark Side, then Obi-Wan is his foil - embracing the Light Side of the Force. Anakin gives in to his hatred, his fear, his anger, his greed & becomes a Sith, while Obi-Wan seems to deny himself these emotions - calculating, plotting each move, especially in dealing with confrontations.
Obi-Wan appears to always choose the "difficult path" - restraining himself from losing control, jumping to conclusions. He reminds me of a good friend of mine who sometimes over thinks every single decision she ever makes. I tend to be more spontaneous, quick to agree (or disagree), fast to act & later deal with the shrapnel. Much like Anakin - which is why I sometimes find myself completely identifying with his fall to the dark side. "That could be me..." and all too easily.
So as we were watching ANH it dawned on me that there is a reason that Obi-Wan is so patient & merciful. Because: he has been to the dark side. Yes. Obi-Wan made a quick & fateful journey to the dark side & it seems that he was not happy with what he saw there - before his eyes or in the mirror. In TPM Obi-Wan digs deep into the dark side to defeat Darth Maul - in fact, it is my belief that if Obi-Wan had not snapped back to his old self just after killing DM, he would have been a more powerful Sith than Anakin could ever dream.
Obi-Wan is full of passion & emotion that he keeps under wraps (especially in his padawan days). You can see all of these emotions boiling just under the surface in TPM - he's anxious, ready, impatient, energetic, passionate, and willing to question his teacher. Does he have a love interest? Well, what man of about 20 years old doesn't oggle at girls? He allowed himself to become angry over Qui-Gon's death & this enabled him to defeat Darth Maul. This is why the Jedi Council has mixed feelings about this victory. But you already knew that...
From that moment on, then, we see a different Obi-Wan. One who tells Anakin "We must be patient", one who is willing to sit back & watch a few moments go by before deciding how best to act. This is why he is a great addition to the Council. He's been to the dark side, he knows what hasty decisions bring to one's soul, and he's not willing to go back there.
Obi-Wan kills in Episodes 2, 3 and the Clone Wars series only when necessary (in war or when his own life is on the line) and shows mercy whenever he can. Choosing the destruction of droids over living beings, hands off scare tactics instead of engaging with light sabers, strolling through the sports bar casually rather than screaming "Everybody be cool, this is a robbery!!" to sift out Zam Wessel. Should I go on?
Sure he kills General Grevious, but GG is definitely "more machine" than organic, and being a key player in the Separatist movement, it was important that GG was removed from the playing field. BUT, the most important "choices" he's made regarding his own character, were those moments where he decided to let his adversary live.
In Episode 2 he hesitated in his combat with Jango Fett. Why? Partly because he caught a glimpse of Boba watching from the cockpit of Slave 1. Obi-Wan may have wanted to kill Jango or at least capture him for questioning, but he wasn't about to do anything in front of the guy's kid. Obi-Wan is a good man, he respects the heart of a child - even the child of a known killer. Letting Jango Fett live is a big moment for Obi-Wan - he chooses life over death and later pays the price for his hesitation.
Episode 3 the big moment of course is when he decides not to finish off Anakin on Mustafar. In fact, he didn't even want to kill his friend in the first place. Obvious reasons there, but even after seeing how evil his friend had become, he
still did not have the heart to slaughter his unarmed friend. Mercy? Torture? I can't decide, but Obi-Wan was not going to let the Dark Side control his actions and no matter who was lying on the lava, killing that person with his own hands would have been a few steps down the dark path. Obi-Wan again chooses light.
Episode 4... we see a wiser, older, very patient Obi-Wan. 20 years on Tatooine have chilled him out quite a bit. He doesn't seem to have to think twice about his actions because he's spent all those years planning these moments. He does not blast his way in or out of Mos Eisley, carefully stowing his lightsaber after saving Luke from walrusman. He does not take part in the killing of the stormtroopers on the Death Star (listen close to the blaster fire coming from the Falcon, I don't hear a lightsaber buzz...) and he chooses to "sneak around" instead of having a "fair fight" to get to the tractor beam. His final decision, to sacrifice himself to Vader so that Luke could live, was the ultimate offering to the Light Side. He & Vader were still fairly matched in the old-man lightsaber fighting skills. That was anyone's victory, but the only way Obi-Wan could prove to the Force that he was 100% "good" was to give himself.
Obi-Wan is a man who has seen the Dark Side, has seen himself in the Dark Side, and knows he wants no part of it. Does that make him weak? A coward? Or just a well balanced Jedi. Personally, I think Sidious was on to something when he explained to Anakin he couldn't fully understand the Force by just studying one side of it....
Obi-Wan is living proof of that theory.