Don't own Babylon 5 either
The envoy was human, polite, and plainly dressed. The death eaters were surprised to see Voldemort treat him with courtesy. The envoy spoke first.
"My associates are very impressed that you found us. We are quite hidden, and did not plan to emerge for centuries. We do have a question, though: what do you want?"
"I want your 'associates' to fight alongside my servants, and spread terror and death among the enemy. Was that not obvious?"
"But that is only a means to an end. What do you want?"
"I want to master death -- to rule it and to escape it."
"To live forever. I see. Does all this fighting achieve that? Usually violence shortens life."
"But it is how I will rule the world."
"In my experience, world rulers spend all their time at court and none of it in the lab. That will make immortality harder. Are you sure you want to rule the world?"
"Yes I want to rule the world!"
"What will you do with it?"
"Establish the order Salazar intended, based on purity of blood."
"But your blood isn't pure. Will you then step down?"
"Of course not! When I rule, my blood will be pure -- by definition. I will be descended only from Salazar Slytherin -"
"- So you want to be pure-blooded? -" the envoy tried to interrrupt.
"- and I will have power, power to make them suffer for what they did!" Voldemort thundered right over him.
"Who? Did what?"
"ALL OF THEM! ALL OF IT!"
"I'm sorry, lord, but I've heard a lot of different ideas here, and until you know what it is you want, we won't be working with you." The envoy vanished.
Voldemort gave a wordless cry of rage, then stalked off to find someone to torture.