Yu Yu Hakusho1992

Elder Toguro:
Bui and Karasu said the same thing as you when they challenged us and were beaten down. They were much prettier then.

[Elder Toguro recalls the moment in a flashback]

Karasu:
Kill me now. That's your only warning.

Younger Toguro:
I'm sorry, but your time of death is no longer your decision, Karasu. You belong to the Toguros now. And until you can argue, you will do as we require.

[Elder Toguro mentally returns to the tournament]

Elder Toguro:
Brother's come to quite prefer people like you to fight on our side, now. No loyalties to confuse. Also...

[indicates Bui and Karasu]

Elder Toguro:
...their desire to kill us keeps them motivated to improve. Brother would find you perfect for us. That's why I swore to spare you. However, Brother's not here at the moment, and we have one most important difference - I always hate keeping my promises.