Vader's Fortress：Why Did Darth Vader HATE The Inquisitors?

Under Vader's stringent tutelage, the Inquisitors underwent rigorous training, during which Vader inflicted severe injuries on many of them, including amputations, blinding, and impalement. Furthermore, it is known that Vader eliminated at least three Inquisitors and expressed satisfaction at the demise of numerous others on Malachor 5, believing their deaths would expunge the frailty within the ranks. The reasons for his hatred was both philosophical and personal. First, the inquisitors, notably the Grand Inquisitor, in a display of haughtiness, asserted to Vader that his allegiance was solely to Palpatine and that he did not take orders from Vader. Vader did not take kindly to this rudeness, swiftly demonstrated his dominance. But perhaps more importantly, Vader perceived the establishment of the Inquisitors as a contravention of the Rule of Two, expressing to Palpatine his conviction that he was superior to all Inquisitors combined.