Originally Posted by
Hctaz
By existing. Undeath is a horrible curse and the death knights are the prime example of this. They share all the burdens that the undead race do but they also have to deal with always being at the call of the Lich King. Lillian Voss has shown us that a strong enough necromancer can control any undead, even those that have gained their free will.
Undeath is a constant state of hunger and pain. You have to find ways to preserve yourself, you can't enjoy life like the living can, and demon hunters have the choice to stop fighting and go back to enjoying peace. Death Knights will never find peace. If they were to die then they'd go to hell such as shown with Sylvanas in her book thing. Not even death will relieve them of their torment. And through it all they have slogans such as "Suffer well" and "Tomorrow is another day". They don't go around reminding people of the pains that they're forced to deal with. I mean their starting zone has them killing one of their former best friend's in life and, from the look of it, they actually gain a bit of sanity and would rather not do so. Their friend actually tells you to kill them so that the Lich King doesn't get suspicious for leaving them alive.