Warning! Spoilers ahead for Obi-Wan Kenobi episode 3
Obi-Wan Kenobi episode 3has potentially shed some light on how Darth Vader ranks his Imperial Inquisitors. Following the loss of the Grand Inquisitor, both Third Sister (aka Reva) and Fifth Brother are vying for Lord Vader's favor for the coveted role that is apparently vacant. While the number each Inquisitor carries as a name was thought to be arbitrary beyond identification, a line from Sung Kang's Fifth Brother suggests that there may be more to it than that.
In Obi-Wan Kenobi episode 3, Darth Vader is seen in his castle on Mustafar, having been alerted to the Third Sister's discovery of Obi-Wan Kenobi. Not only does he promise her the rank of Grand Inquisitor once Kenobi is captured, but he also promises that she won't live to regret her failure should Obi-Wan escape. Incredibly ambitious, Reva is eager to please Vader and claim the Grand Inquisitor's seat of power as her own. However, it seems as though she's not the only one who believes they're owed.
Related: How Powerful Reva Is Compared To Other Inquisitors
Angered that Third Sister spoke with Darth Vader directly, Fifth Brother claims that he is the next in line to become the Grand Inquisitor. Combined with the Grand Inquisitor's prior comment that Third Sister is "the least of us," Fifth Brother suggests that the hierarchy amongst the Inquisitors is that the higher their number, the higher rank they have. While this might have some truth about how Darth Vader's Inquisitors are ranked, it seems the Sith Lord is more interested in rewarding results and brutally punishing failures regardless of any kind of perceived rank the Inquisitors think they have.
As far as this idea relates to other Inquisitors not seen
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