So, why'd he have a child in the first place?

Question

In The Cursed Child,

Delphi is revealed to be Voldemort's daughter.

As she explains:

Delphi: I am from the future. The child of Bellatrix Lestrange and you [(Voldemort)]. I was born in Malfoy Manor before the Battle of Hogwarts. A battle you are going to lose. I have come to save you. (Harry Potter and the Cursed Child - p.307 - Little, Brown - Act Four, Scene Eleven)

But why? Why did

Voldemort, of all people,

have a child in the first place?

He does not love, he considers himself supreme, he is arrogant, he does not need a right-hand man/woman, and he has absolutely every intention of immortality. Even with the Potter boy chipping away at his Horcruxes, surely he would feel no need for an heir?

Answer 1

Voldemort may have wanted to carry on the bloodline of Salazar Slytherin

Voldemort was the descendant of Salazar Slytherin, from his mother's side through the Gaunts. His grandfather was Marvolo Gaunt, and his mother was Merope Gaunt. We know that Voldemort had strong thoughts on blood purity, even if he was a halfblood himself.

You think I was going to use my filthy Muggle father’s name forever? I, in whose veins runs the blood of Salazar Slytherin himself, through my mother’s side? I, keep the name of a foul, common Muggle, who abandoned me even before I was born, just because he found out his wife was a witch?

_{-Harry Potter and the Chamber of Secrets}

He would have been proud to carry on the noble line of Slytherin through Delphini. It might have also served to cancel out his sense of shame in having a muggle father.

Answer 2

It's not like fathering a child is always a deliberate choice. He may not have planned anything except to take his pleasure. Bellatrix on the other hand has obviously reasons to "forget" whatever the wizards use for birth control.

Answer 3

I literally don't know what to think about it. I was always convinced that he:

• considered needs like sex beneath his dignity. he always presented himself as a sort of God-figure, or at least a being much better than a mere man, so I assumed he was indifferent to most of common "man" temptations (GOF, ch.1 - on the contrary - if we look at the Greek Pantheon and the concept of anthropomorphism, him feeling and accepting lust, but still thinking about himself as a god/superman, is more understandable)

• would see his child as a potential danger, especially when the child (in this case Delphi) had better genetic constitution than him (Bellatrix was a prodigious witch, Voldemort's father - an ordinary muggle). That means Delphi was not only the next Heir of Slytherin with toujours pur heritage from her mum's side, but theoretically, she could have much more magical power than Voldemort himself. So why take the risk and create recklessly a new unnecessary threat? Or maybe he wasn't interested in making babies at all. And Delphi was a surprise.

But then, why did he let her live? I found this Q&A:

What exactly happened when Voldemort used the Avada Kedavra curse on Harry in the forest?

Again, Voldemort violated deep laws of magic he did not understand, but there is more to it than that. Having taken Harry’s blood into himself, Voldemort is keeping alive Lily’s protective power over Harry. So Voldemort himself acts almost like a Horcrux for Harry – except that the power of Lily’s sacrifice is a positive force that not only continues to tether Harry to life, but gives Voldemort himself one last chance (Dumbledore refers to this last hope in chapter 35). Voldemort has unwittingly put a few drops of goodness back inside himself; if he had repented, he could have been healed more deeply than anyone would have supposed. But, of course, he refused to feel remorse.

MV: Why was it important to you, Jo, to write about the cruelty and inhumanity?

JKR: I'm not sure why. But it was what I wanted to write about most. And it's about choice. And you are shown that Voldemort. Ummm... I suppose we're going to call him a psychopath. But he's so, in many ways, he is what he is and he's beyond redemption. Although this being Harry Potter and because I can take liberties because I have magic in my world, it is shown at the very end of the book that he did have a chance for redemption because he had taken into his body this-- this drop of hope or love-- Little love (but still) was put in Voldemort when he took Harry's blood at the Little Hangleton graveyard. He was given a tiny bit of humanity.

According to JKR, Lily's sacrifice gave Voldemort a chance to repent. I wonder if this small portion of goodness could have also prevented him from killing his unborn innocent child.