A few months ago I wrote a review of the Star Wars Machete Order, the definitive way to watch Star Wars. Episodes 4,5,2,3,6 set up the Star Wars narrative at it's most satisfying and, if you have access to nothing else in the Star War universe, the way you'd get the most out of Star Wars. But there is another. Way, I mean. And it involves adding three episodes from the cartoon The Clone Wars: the Mortis trilogy, season 3 episodes 15-17. This, in my view, completes the story by bringing in the last bits of what you'd need to know from what is implied in the other episodes but brought out here fully.
Anakin, Obi-wan, and Anakin's padawan Ahsoka Tano are doing a mission in the Clone Wars when they get side-tracked by what's essentially the three gods of the force: the Daughter (Light side), the Son (Dark side), and the Father (who balances them both). The Father and Daughter's aim is to get Anakin to accept his rightful place as the chosen one, replacing The Father. These three individuals are so overwhelmingly powerful in the Force that they must stay on the planet Mortis or else overwhelm the rest of the galaxy with their power, and it is the Father's unenviable job to keep his progeny in check. Except now it's Anakin's turn. Anakin refuses, and the tragedy is played out to the harm of everyone in the galaxy.
I'll avoid spoilers as much as possible except to comment on the chief event. In the last episode of the Mortis trilogy (which I'll dub Episodes 2.5) the Son gets the drop on Anakin and shows him all the evil he'll do in the name of the Empire, overwhelming Anakin. In that moment of emotional weakness the Son brainwashes Anakin into joining his side, promising him that together they can stop the bad events that Anakin saw from happening. How does it all play out? Go watch it, I ain't ruining the rest for you! It's on Netflix so it's not hard to find.
But here's where things get interesting. Take a look at Anakin brainwashed here:
Does this look familiar? It should.
Anakin Skywalker was brainwashed by Lord Sidious and it never fully wore off until Episode 6. Anakin is not doing things of his volition. Canonically speaking, to the best of my knowledge, that's what the yellow eyes mean. It's subtle in Episode 3, but 2.5 makes it clear. With the knowledge we get from 2.5 and 3 we can say a few things about brainwashing in the Star Wars universe:
1) It is not mind control. It's putting your influence where it doesn't belong and that person warping themselves around your influence. Anakin did terrible things in Episode 3, but he did them as Anakin, not as a mindless robot. He just had someone else working in the background to influence him.
2) Brainwashing can only happen at moments of emotional weakness on the part of the subject. You can't just force your way in; it's impossible for even someone as power as The Son. What you have to do is wear them down and worm your way into their consciousness and then, at their weakest, plant a thought and force an inception. That person then incorporates it.
3) To undo the brainwashing you remove the inciting incident from their memory, thus removing the toe hold.
Which brings me to Return of the Jedi. Armed with this new knowledge about how brainwashing works, the picture's a lot clearer: Anakin has been taken advantage of by Palpatine and has committed some of the most horrific acts of evil that one can do. But the question is: is the good side of Anakin completely gone? Luke doesn't think so. Unlike his mother, who saw the offer as a sign of how far gone Anakin was, Luke sees it as the one saving grace Anakin has left.
So he surrenders himself up to Vader and starts chipping away at the armor. Unlike The Father, who undid Anakin's first bout of brainwashing by just removing the inciting memory, Luke goes straight for Anakin with his own Force influence, trying to counteract the effects of the brainwashing without removing any memories. Including Episode 2.5 adds an entire layer of subtext into Episode 6 that makes Luke that much more impressive. He not only resists Palpatine but rescues his father by using the first trick Obi-wan showed him back in Episode 4: persuading the weak-minded.
And, after all that you've seen Anakin do, what is he if not weak-minded?
Now, there are some people who are going to have issue with modifying the Machete Order. The first (and biggest) objection is that Episode 2.5 is from a long running TV show, The Clone Wars. I've got good news: these are some of the most self-contained episodes in the entire show. Most of the developmental arcs do not impact these three episodes. Ninety-nine percent of what shows up in 2.5 is completely new. So context really isn't a big deal for what came before those 3 episodes. Another argument might be that, with the inclusion of 2.5, Episode 1 becomes necessary, because of 2.5's Qui Gon Jinn appearance. But it's such a minor event (especially in comparison to Snips's appearance) it's more of a nitpick, at least in my opinion. If you wanted to you could show Episode 1. But that would require not loving the people you're showing this epic sprawl to. Which doesn't make sense; who else would you show this to but someone you love?