For the most part, the Vader comics are canon. They contribute to the broader narrative and lore of Star Wars and are recognized as part of the official storyline.
Typically, Vader's redemption starts with a moment of self - reflection. Maybe he witnesses an act of extreme cruelty by the Empire that makes him question his place. Then he begins to reach out to the Light Side, often through small acts of kindness or defiance against the Emperor.
One of the best Darth Vader novels is 'Lords of the Sith'. It really delves into the relationship between Darth Vader and Emperor Palpatine. It shows their power dynamics and Vader's complex feelings towards his master. Another great one is 'Darth Vader: Dark Lord of the Sith'. This novel explores Vader's early days as a Sith, his training, and his internal struggles as he fully embraces the dark side.