Olaf
Spoilers for the original Hellchild series.
Olaf was already dying when somebody offered him forever. That's worth remembering when he starts treating everyone else's blood like something he's entitled to take.
Hellchild shows him as a Viking warrior, badly wounded in a snowy battle, with his enemies closing in. A vampire cuts through the soldiers around him and offers him the blood of life. This is Jerrik, the vampire who becomes his sire. He calls Olaf his son, and centuries later, Olaf still means it when he calls Jerrik his father.
By then, though, Olaf has found something that matters to him more than following his father's rules. He's drinking from other supernatural beings, and their blood gives him access to power his own kind has been avoiding. He isn't satisfied with staying alive forever. He wants to see what else he can get out of it.
The way he treats the witch Lyra makes that pretty clear. He crosses a boundary she already gave him, refuses to let her leave, and survives the magical attack she expects to kill him. Then he starts using magic himself. She ends up imprisoned alongside other supernatural captives, including Artemis. These aren't guests helping him explore some new possibility. He's keeping people there to feed on them.
And then he finds Angelica.
She hits hard enough to send him flying and tears his throat open. He heals it with magic, so she has to stop and ask what he's supposed to be. He gives her an answer she badly needs: a vampire, like him. He offers shelter, a place with his crew, and help with her vengeance.
It's a useful sales pitch for somebody who has just come back from the dead and doesn't understand the world around her. It's also a lie. Once she's chained up, Olaf admits he hasn't actually met anything like her. He's noticed the heartbeat, the strength, the fangs. He doesn't understand everything about her yet, but he understands that he wants it.
Jerrik's arrival exposes how far Olaf has gone. His sire rejects the supernatural blood as polluted and warns that their immortality depends on keeping their blood pure. Olaf sees that as throwing power away. Jerrik sees Olaf endangering himself and drawing the attention of the vampire establishment.
Neither of them is arguing for the prisoners. Jerrik wants them slaughtered, and Olaf wants to keep using them. When Jerrik kills Lyra, Olaf's objection is about what her blood could do.
There is a real family relationship buried in that confrontation, which is what makes its ending ugly. Olaf talks about their years together and insists Jerrik is his father in a way other sires aren't. Jerrik offers to cover for him and have him rule alongside him. Then Angelica offers something else: her blood, her power, and an alliance against Hades.
With Jerrik restrained, Olaf decides he'll do the killing himself. He drives the stake into the vampire who saved his life.
That doesn't make Angelica his equal. Once he has access to her blood, he turns on her too. By the final fight, he's boasting that anything her blood can do, he can do. He breaks her neck, and she gets back up. He uses her own weapon to impale her, and she uses that position to force him back against a tree, keeping them pinned together as sunrise approaches.
That is where his confidence finally runs out. Olaf burns. Angelica doesn't.
I like that his ending comes back to something he never properly understood about the person he was using. He noticed her heartbeat. He noticed the weapons and the power. He knew she wasn't a normal vampire, and still convinced himself that taking her blood meant he'd caught up with her. He gambled his own immortality on that assumption after killing the person who originally gave it to him.
Olaf
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