This article contains spoilers for Obi-Wan #1.
A new Obi-Wan duel Darth Vader again - twice.
For all that is the case, though, Obi-Wan didn't always recognize the influence of the Sith in his life. Like all the Jedi, he was blind to the fact the Supreme Chancellor he was working alongside was secretly a Sith Lord. He saw so many hints his apprentice Anakin Skywalker was falling to the dark side, and yet he chose to ignore them, indulging in an attachment of his own that meant he never did his duty. The Jedi who fought the Sith on so many occasions unwittingly helped Darth Sidious' plans come to frutition.
Surprisingly, Obi-Wan #1 by Christopher Cantwell and Ario Anindito reveals Obi-Wan's first brush with the Sith may have been back when he was a Padawan. The comic appears to be set immediately before the events of the first Star Wars film, with Obi-Wan sensing what he describes as "a surge in darkness" that makes even a Jedi Master afraid. It's implied this is the arrival of Darth Vader in orbit, with the Empire pursuing the Tantive IV and the Death Star plans. Obi-Wan recognizes the feeling, a sense he first felt when he was a Youngling in the Jedi Temple, and his best friend Gehren was having nightmares of her father in pain; she decided these were prophecies, and left the Jedi Order, with Obi-Wan unable to stop her doing so. The implication is that the dark side was manipulating Gehren - and, indeed, that this was most likely being done by a Sith. Presumably the Sith monitored the Jedi Temple, encouraging any they sensed possessed attachment to leave the Order by giving them nightmares they believed to be prophetic.
There's a striking parallel between Gehren's dreams and Anakin Skywalker's experiences, ing the long-standing fan theory that Palpatine projected the visions that plagued Anakin into his mind; dreams first of the death of his mother Shmi in Star Wars: Episode II - Attack of the Clones, and then of his beloved Pé in Star Wars: Episode III - Revenge of the Sith. Sadly, in Anakin's case Obi-Wan did not intrude; he brushed aside Anakin's worries about his mother, unaware of where the attachment would lead him, and seems to have turned a blind eye to Anakin's marriage to Pé - ensuring he would never be told about those later nightmares.
It's easy to be critical of Obi-Wan Kenobi; even he blamed himself for pursued her into Coruscant's underworld in an attempt to save her. A pattern was set in Obi-Wan's life in Star Wars; whenever he recognized the dark side, he would oppose it. The only problem was that he didn't always recognize it - and sometimes he didn't allow himself to do so.
Obi-Wan #1 is on sale now from Marvel Comics.