There’s some evidence to support the Plagueis theory, including The Stranger’s use of cortosis, which the Sith Lord mined for his master Darth Tenebrous in Legends. Then there’s The Stranger’s base of operations on an ocean planet. In Legends, Plagueis mined cortosis on the ocean planet Bal’demnic, which is also where he eventually killed his master. Are these connections more than just coincidence?
Not Darth Plagueis, But Darth Tenebrous?
While Plagueis is the most popular theory regarding The Stranger’s identity, others think he’s actually Darth Tenebrous, Plagueis’ master as established in both current canon and Legends continuity. Yes, Tenebrous was a Bith in Legends, but that’s not set in stone in canon, and if it hasn’t been established onscreen anyway, there’s nothing stopping the show from making Tenebrous a human Sith Lord.
Just like Plagueis, Tenebrous had a connection to cortosis and Bal’demnic in Legends. The main reason some believe The Stranger is Tenebrous is because of the show’s place on the timeline. In Legends, Tenebrous was the reigning Sith master until 67 BBY (Before the Battle of Yavin), when Plagueis killed him. Since The Acolyte takes place in 132 BBY, Tenebrous would fit this specific time period, if the show decides to follow what was established in Legends.
Mother Koril Is the Sith Master Pulling All the Strings
In the penultimate episode of the season, we learned what really happened on the planet Brendok 16 years before the start of the show. A series of very bad choices led to the slaughter of a coven of witches inside their secret base. It’s revealed that Mother Aniseya died by Sol’s hand, while the rest either perished in the fires accidentally started by Mae or were killed by Master Indara through the Force.
But there’s one witch we never actually watched die in the episode: Mother Koril, Osha and Mae’s other parent. While the series made a point to show the bodies of witches littering the floors of the base, Koril was not among the victims. Instead, her whereabouts are currently unknown, leading some to believe she may be the big bad of the series, pulling the strings from the shadows as the Sith master while her apprentice, The Stranger, does the dirty work and recruits Osha to the Sith cause.
Koril also happens to be Zabrak, the same race as Darth Maul. Surely that’s no accident?