"There is no higher pleasure...That means a great deal, Bellatrix, from you"

What do you think Voldy meant when he said this? What could be be referring to as the competing "high pleasure"? Torturing people? Something more lewd/banal, like receiving affection back from Voldy?

I've been meaning to ask this for ages, and have wondered about it ever since reading DH.

Let's ignore Cursed Child momentarily and base it off the original series.

Thoughts and musings?