"Of course Tridentarius saw you," Harrow snapped, with predictable waspishness. "Any necromancer worth their lymph would have seen you. I'm only surprised the other twin didn't."
"I was all swaddled up like a perfect Ninth House mummy, in that absolute pit of a stairwell," protested Gideon. She'd expected the news that the pallid Third twin had caught her lurking in the area of locked door X-203 to provoke more trademark Nonagesimus paranoia, and less trademark Nonagesimus scorn.
But no such luck. Scorn was the order of the day. "She sensed your thalergy signature. It was foolish of you to think you could conceal yourself from a necromancer, and idiotic to put yourself in a situation where -- you must have known this, Griddle," Harrowhark interrupted herself, apparently in response to the gobsmacked expression on Gideon's face. "You've never been able to hide from me once in your whole life. Didn't you realize why?"
Gideon found herself feeling unexpectedly angry, uncomfortably exposed, and monumentally fed up with Harrowhark's infinite unfolding layers of horribly invasive secrets. "Yeah, because you're a stack of evil bats glued together inside a shitty cloak! I didn't think just anyone could see me through walls and shit!"
Harrow sniffed disdainfully, as though it were Gideon's fault for not knowing the details of her creepy powers that she'd deliberately obfuscated. "Anyone can't. It takes a sensitive and well-trained necromancer to detect a thalergy signature without supporting sensory input. But you do happen to have a higher-than-average thalergy concentration." Thoughtfully she added, "Perhaps I'll offer you as a lab specimen to the Sixth in exchange for their keys."
Gideon ignored this, knowing as she did that Harrow wouldn't have offered the Sixth a glass of water if they were drowning in magma. With that reminder, her anger abated a little. Getting mad at Harrowhark for keeping secrets was like getting mad at gravity for making something heavy fall on your foot; it wasted your breath, maybe made you feel a little better, but didn’t un-crush any crushed bones or un-violate Gideon’s privacy and peace of mind.
Curiosity crept up in anger's place. "Higher than average? Does that mean that in your necro-vision, I'm extra hot?"
Harrow rolled her eyes so hard it made her nose start to bleed again, just a little. She scrubbed at it irritably with her sleeve, which, gross. Thickly through the trickle of blood she said, "In a strictly thermal sense, yes. Aesthetically you're still awful and vapid."
"Okay, no, but I want to know, what does that look like? If Tridentarius saw me naked or something --"
"She didn't -- for God's sake, Griddle, must you always be such a cretin?" Harrow's voice was sharp and snappish, of course, but to Gideon's considerable surprise the bite in it wasn't actual hatred, or even annoyance. It was more along the lines of the instinctual, half-whining protest of a sleeper demanding five more minutes without any expectation of the demand being met. Harrow even appeared, possibly as a side effect of the bizarre and multiplicitous traumas she had inflicted on herself in Canaan House's haunted basement, to be considering her cavalier's question.
After a very strange and tense (for Gideon) silence, she said almost dreamily, in the bored tones of a child reciting a lesson, "Thalergy concentrates in blood, and in marrow, and extends in a bloom that fades rapidly as it radiates outward from the point of greatest intensity. Your particular personal signature is in quality very like a candleflame, but it moves, as your blood moves. The overall effect is a perhaps best described as -- a little like an aurora."
She said this as though describing what a femur looked like to a very stupid necromantic novice about to open up her first corpse, and without a trace of anything so un-Harrowhark as sentiment. Even so, Gideon couldn't help but stare at her. The only thing she could think to say was, "You've never seen an aurora."
"Nav. Your tiny, vestigial brain would shrivel and die if you tried to use it to comprehend even the least of the vast and perilous sepulchral secrets I am privy to. You have no conception of what I have seen," intoned Harrow, who would have flayed herself alive with bone flechettes before admitting that she'd seen an illustration of an aurora in one of Gideon's comics, that she'd stolen and read in a fit of fascinated disgust when she was eight. Most of it had been more or less incomprehensible, and the rest had been filthy Cohort slang that Harrow, even at age eight, had more than enough anatomical knowledge to parse. But the illustrations had really been quite good.
"Yikes," Gideon said, more or less automatically. And then, "Should I stick around? You know, to be your nightlight, my abyssal archduchess?"
One of the skeletal arms holding Harrow upright made a gesture that communicated with impressive clarity what Harrow would do to Gideon's spine if she stayed. Gideon retreated to her nest in the outer room of the Ninth quarters; but she stayed awake for an uncomfortably long time, unable to stop thinking of the way Harrow had said like an aurora.
Everything was weird and un-normal. The Sixth seemed kind of cool and they probably hated her for being a trash cav, Harrowhark had nearly died in a bone and Gideon had actually been upset about it -- was still upset about it, quite honestly, which was even more upsetting -- and now even the past, which should have been as solidly fixed and immovable as the Stone itself, was gaping full of fissures and holes. To have been seen by Harrow as a bright light in the shadows of Drearburh for all those years…
It was way too fucking weird to contemplate, is what it was, and she'd never been more grateful to fall asleep.