Example: https://www.youtube.com/watch?v=sFUPrtTlE5g

The individual who became known as the Eighth Brother originally occupied a position within the Jedi Order. At some point after the Galactic Republic was reorganized into the Galactic Empire, he was inducted into an Imperial agency of Force-sensitive assassins called the Inquisitorius, which was tasked with hunting down and eliminating any Jedi who survived Order 66. To accomplish this, he and his colleagues were trained by The Grand Inquisitor in their training center in the Works, but soon fell under the command of Darth Vader when Darth Sidious first demonstrated the Inquisitorius to Vader, who continued their training in the ways of the dark side of the Force. The Grand Inquisitor informed Eighth Brother and his colleagues that they had two masters, Eighth Brother in response proclaimed that they only served Sidious, but was soon countered by the Grand Inquisitor who stated that times had changed