A Star Wars Prequel Character Made His Debut In A Comic – And Underwent A Redesign
One of the best and most devastating moments in "Star Wars" is Order 66 in "Revenge of the Sith." To close out the Clone Wars, the clone troopers that have fought beside the Jedi turn and shoot their commanders in the back, on orders from Chancellor Palpatine/Darth Sidious.
The most memorable death is Jedi Aayla Secura on the jungle planet Felucia, shot in the back by Clone Commander Bly and his brothers-in-arms. In one draft of the script (but not the finished film), Aayla is scouting for enemy droids and asking Bly for his input before he shoots, emphasizing her being taken by surprise. The Felucia scene would also feature Bly and the clones fragging Jedi Barriss Offee, but this was deleted, so the "Clone Wars" and "Tales of the Jedi" cartoons took that character in another direction.
That wasn't the only change to the scene. You see, in "Revenge of the Sith," the clone troopers have personalized armor depending on what planet they're on. Obi-Wan Kenobi's troops on Utapau have orange highlights, while the Kashyyyk battalion has camouflage green armor. "The Clone Wars" carries this over; Anakin Skywalker's troops (like Captain Rex) have blue highlights on their armor.
Bly and the Felucia troops have yellow markings on their armor. According to StarWars.com, their CGI models were originally designed with red armor. However, yellow looked better in the swampy jungle environment of Felucia (it also makes sense in-universe; the clones would be trying to camouflage themselves within their surroundings) so Bly's design was recolored. Bly's original character model was instead used for a different clone commander, Deviss (who doesn't appear onscreen, only in reference books and the movie's toyline). The change evidently happened quickly enough for Bly to have movie-accurate yellow armor when he debuted in the "Star Wars: Republic" comics.
Star Wars: Republic
The video game "Star Wars: Battlefront II" (set during the Clone Wars) features a mission on Felucia. The clone narrator says of Aayla and his betrayal of her: "When her death came, I hope it was quick. She'd earned that much. [...] It was a good thing we were wearing helmets because none of us could bear to look her in the eye."
"Star Wars: Republic" (by writer John Ostrander) also fleshes out Aayla's relationship with her troops, Bly especially. It should be noted that Ostrander is the one who created Aayla with artist Jan Duursema; she debuted in "Star Wars: Republic" issue #19 (published in 2000) as the apprentice of Jedi Master Quinlan Vos. (Ostrander and Duursema nicked Vos' design off a "Phantom Menace" extra, who retroactively became Vos.) Duursema originally envisioned Aayla as a fish alien before remaking her as a sexier, blue-skinned Twi'lek. This change is likely what made Aayla into a movie star — and ultimately signed her death warrant.
George Lucas noticed Aayla and brought her over into the films. During the finale of "Attack of the Clones" where hundreds of Jedi fight on the planet Geonosis, Lucas wanted to have "exotic" looking Jedi, not just human ones. Since the crew already had plentiful Twi'lek costumes and make-up (the race are frequent background characters) and a pre-existing design/character with Aayla, they put her in "Attack of the Clones" to fill out the Jedi ranks. You can also hear Obi-Wan mention a "Master Vos" in "Revenge of the Sith," but Quinlan didn't make it onscreen again.
The Tragedy of Commander Bly the Unquestioning
Ostrander and Duursema kept using their creations as their comics took to depicting the Clone Wars in more depth than the movies could. To keep Vos as a star, Ostrander wrote a story where the Jedi goes undercover as a disciple of Sith Lord Count Dooku, with his loyalties shifting as the dark side corrupts him.
It was surely Lucas who decided to kill Aayla in "Revenge of the Sith." He wrote the movie and needed recognizable Jedi (with pre-existing costumes/actors) to be the onscreen victims of Order 66. Who knows, he may have even thought Aayla's prominence in the comics would give her death some extra oomph for the fans without the movie needing to spotlight her more. When her creators got word that Commander Bly would kill Aayla in "Revenge of the Sith," they set up the relationship (either on their own initiative or Lucas'). Bly first briefly appears with Aayla in "Republic" issue #65, then gets a starring role in #68, titled "Armor."
Aayla and Bly are dispatched to planet Honoghr to retrieve valuable intelligence. They meet Vos, who is still working for Count Dooku but claims to be on the Republic's side. Aayla wants to trust her mentor but Bly is suspicious. Bly narrates the issue, describing cracks in the symbolic "armor" of each individual. In Bly's closing lines, he describes his own obedient attitude, foreshadowing how he'll lethally betray Aayla during Order 66: "Get the order and execute it. Let the generals sort out the rest. Works for me."
"Star Wars: Republic" is now considered "Legends," and so non-canon to the films/TV shows, but all you Bly-heads out there should still read it.