The Dying of the Light by Derek Landy

But, of course, now it’s too late.”
    “Argeddion is alive,” said Darquesse.
    Tarry frowned. “No. He’s dead. Skulduggery Pleasant killed him when—”
    Darquesse spoke over him, her words calm. “Officially, Argeddion died following the confrontation with those super-powered hooligans he’d created. Skulduggery finished him off. That’s the story that was circulated.”
    Tarry sat forward. “It’s a lie?”
    “They couldn’t kill him,” Darquesse said. “They didn’t know how. So they rewrote his personality, convinced him he was normal, and hid him away. Even I don’t know where he is now.”
    Tarry was quiet for a moment. “The
Hessian Grimoire
,” he said. “That should help you find him.”
    “How?”
    “You have a deep understanding of energy, Darquesse. Your understanding might even surpass my own.”
    “Oh,” said Darquesse, “it does.”
    A faint flicker of irritation crossed Tarry’s features. Sanguine noticed it. And if Sanguine noticed it, then Darquesse certainly did. That faint flicker of irritation had most likely just signed Mr Tarry’s death warrant.
    “But once you read that book,” Tarry continued, “you will know how to detect and track energy. Argeddion found out his true name, the same as you. For all intents and purposes, he is lit up like a beacon – providing you know how to look for him.”
    “The
Hessian Grimoire
sounds like the answer to all my prayers,” Darquesse said. “Thank you, Nestor. You have been most helpful.”
    Tarry stood, but wavered. Finally, he plucked up the courage to ask, “Can I come with you? When you find Argeddion, I mean. You’ll need a Remnant to possess him, won’t you? So he’ll talk? I would do anything for the opportunity to peek inside his mind. He is … astonishing.”
    “He is,” said Darquesse. “But I’ll just have to use my other Remnant to possess him. I’ve kind of grown bored with you.”
    Tarry paled, making his black veins stand out even more. “What?”
    “You’ve just rubbed me up the wrong way,” Darquesse explained.
    “I … I’m sorry. I apologise. I didn’t mean to—”
    “It’s not your fault,” said Darquesse as she got to her feet. “It’s mine. I’m probably just overly sensitive. I’ve only been studying quantum mechanics for a few days, and … I don’t know. Any kind of criticism or – what’s the word? –
irritation
shown is just … it’s more than I’m prepared to accept right now.”
    Tarry backed away. “I wasn’t irritated. I wasn’t, I swear. And I would never criticise you. Never. The amount you’ve learned in such a short space of time is hugely,
hugely
impressive.”
    Darquesse narrowed her eyes. “Oh, I do not like being patronised.”
    She raised her hand and Tarry exploded into nothingness.
    Sanguine jerked back in astonishment. No blood, no meat, no bones. Nothing.
    “There,” Darquesse said, a smile on her face once again. “I feel so much better now.”
    “What did you do to him?” Sanguine asked. “Where is he?”
    “He’s still here,” said Darquesse, her fingers playing lightly against the air. “His atoms are spread out around the room. It’s funny, isn’t it? Group all those atoms together and Nestor has a body. Separate them, and you have to ask where he’s gone. I can put him back together, if you’d like.”
    “You could do that?”
    “Sure. I think. Putting things back together is a lot harder than pulling them apart, but I’ll do my best.”
    Darquesse chewed her bottom lip as she focused. A moment passed, and she closed her fist, and Tarry reappeared, blurring into existence. He staggered, eyes glassy, and dropped to his knees.
    “He’s in shock,” said Darquesse. “Either that or he’s a vegetable. The brain is tricky. I can see how the body reassembles, how the nervous system fits, but the brain will take a little more practice. Want a seat?”
    Sanguine looked at her. “Sorry?”
    “A seat,” she said. “You want one?