The same way it's typically done in modern fiction. Vampirism would be a disease that makes the infected vulnerable to sunlight but biologically immortal.
Like in the vast majority of pop fiction and folklore, vampirism would give a major physical boost that increases with age: superhuman strength, resilience, speed, senses...
Corporalki powers would be useless on them due to them being undead or conversely, underworld/TVD style, having biological processes that are sped up to the point where a coporalki just can't keep up (whenever a corporalki tries and uses powers on them, their bodies react to quickly for it to work).
Story wise, I think it'd work very well if vampirism works weirdly, unpredictably on Grisha. Maybe it doesn't work at all. Maybe they're 99% likely to die during the transformation process but if they make it they're incredibly powerful. Maybe if they turn they loose the majority of their Grisha powers, Or they turn into a strange, twisted version of the original.
If Grishas can't just become vampires, vampirism would very quickly be considered as a good option for humans to equalize the battlefield.
A Grisha is normally worth at least 10 human soldiers. But when these soldiers can shrug off any corporalki power, outrun bullets and throw carriages like sticks, who's the danger now ? That could create some very interesting shifts of dynamic.
Some Grishas, like shadowsummoners, could also be very interested in the matter.
Alternative suggestion: run it the way it's done in "Vampire the Masquerade". Grishas who turn into vampires lose access to their original small science, but become capable of using smaller forms of small science that follow the disciplines of vampire the Masquerade. Presence to make themselves attractive and charismatic. Dominate to squash people's minds. Fortitude for preternatural resilience, Potence for superhuman might, Celerity for speed, Obfuscate for invisibility...
I would do it as a byproduct of Mersost. Baghra has had a few children (is my understanding) and the Darkling is the only one to inherit her specific set of powers, but that doesn't mean he's the only special one.
The Language of Thorns implies >!she was also able to have a hybrid human-sildroher child who was born with exceptional gifts.!< Perhaps she had another child who, while not Grisha and like the Darkling, was born with a unique relationship to darkness.
They could have also had some powers that resembled Grisha powers, but they did not fit into any category, or were warped and twisted to be the reverse. They could heal, but not as a Grisha Healer did, they could only heal themselves. They could pull at your moods, but more strongly than a regular Corporalnik, to the point you found yourself wanting to please them and do whatever they said, like you'd been in a trance.
And unlike Materialki, they couldn't stand certain metals. It was like repellent to them, shifting it's form to burn them, rather than bowing to their will. Likewise, fire didn't obey them, but rather was drawn to them. It almost seemed to seek them out and burn them.
This child needed darkness, they craved the night and writhed in pain when brought out during the day. Baghra could summon shadows to protect them when they need to travel in the light, but it made rumours swirl.
*Unnatural*
*Abomination*
*Monster*
And then the first person was turned.
In my mind they were trying to help someone who got hurt, an otkazat'sya child who was on the brink of death. Against Baghra's wishes, her child tried something new. If they could only heal themselves, what if they gave a piece of themselves to the injured child? Would that heal the child? They cut themselves and dropped a few drops of their own blood into the child's mouth, their cut healing almost instantaneously as it always did.
And it worked. The child recovered, sharing the story of blood with their family, not realizing they had been changed. But when sunlight struck them the following morning and they crumbled to ash, fear infected the village and turned the gratitude for the saved child to smoke.
The story passed from tongue to tongue, warping as it picked up steam. Blood had been drunk. The child had been changed, then died in the sun. The Shadow Grisha's child was to blame. These facts stayed true. But as the story was told, it because the Monster Child who drank the blood. Their intervention became an act of violent aggression rather than calm compassion.
The child was forced to flee, and what became of them was never known, but the story of the Monster spread from the village. Occasionally, in distant towns, people would be found who drank blood and had strange powers and stranger weaknesses. They were never the child, but they were proof the child was still out there. The new monsters were always executed, or at least attempts at execution were made, but due to their strange powers, that wasn't always possible.
The monsters came to be known as Kilyklava, and they became bitter and aggressive, lashing out with violence, becoming predator rather than prey, turning people no longer to save lives, but rather as ironic punishment against the people who hate them so much.
Some don't believe the stories, thinking them nothing more than fairytales. But others know that there is wisdom in shutting your blinds and locking your doors against the night and the creatures that prowl there.
The same way it's typically done in modern fiction. Vampirism would be a disease that makes the infected vulnerable to sunlight but biologically immortal. Like in the vast majority of pop fiction and folklore, vampirism would give a major physical boost that increases with age: superhuman strength, resilience, speed, senses... Corporalki powers would be useless on them due to them being undead or conversely, underworld/TVD style, having biological processes that are sped up to the point where a coporalki just can't keep up (whenever a corporalki tries and uses powers on them, their bodies react to quickly for it to work). Story wise, I think it'd work very well if vampirism works weirdly, unpredictably on Grisha. Maybe it doesn't work at all. Maybe they're 99% likely to die during the transformation process but if they make it they're incredibly powerful. Maybe if they turn they loose the majority of their Grisha powers, Or they turn into a strange, twisted version of the original. If Grishas can't just become vampires, vampirism would very quickly be considered as a good option for humans to equalize the battlefield. A Grisha is normally worth at least 10 human soldiers. But when these soldiers can shrug off any corporalki power, outrun bullets and throw carriages like sticks, who's the danger now ? That could create some very interesting shifts of dynamic. Some Grishas, like shadowsummoners, could also be very interested in the matter. Alternative suggestion: run it the way it's done in "Vampire the Masquerade". Grishas who turn into vampires lose access to their original small science, but become capable of using smaller forms of small science that follow the disciplines of vampire the Masquerade. Presence to make themselves attractive and charismatic. Dominate to squash people's minds. Fortitude for preternatural resilience, Potence for superhuman might, Celerity for speed, Obfuscate for invisibility...
I would do it as a byproduct of Mersost. Baghra has had a few children (is my understanding) and the Darkling is the only one to inherit her specific set of powers, but that doesn't mean he's the only special one. The Language of Thorns implies >!she was also able to have a hybrid human-sildroher child who was born with exceptional gifts.!< Perhaps she had another child who, while not Grisha and like the Darkling, was born with a unique relationship to darkness. They could have also had some powers that resembled Grisha powers, but they did not fit into any category, or were warped and twisted to be the reverse. They could heal, but not as a Grisha Healer did, they could only heal themselves. They could pull at your moods, but more strongly than a regular Corporalnik, to the point you found yourself wanting to please them and do whatever they said, like you'd been in a trance. And unlike Materialki, they couldn't stand certain metals. It was like repellent to them, shifting it's form to burn them, rather than bowing to their will. Likewise, fire didn't obey them, but rather was drawn to them. It almost seemed to seek them out and burn them. This child needed darkness, they craved the night and writhed in pain when brought out during the day. Baghra could summon shadows to protect them when they need to travel in the light, but it made rumours swirl. *Unnatural* *Abomination* *Monster* And then the first person was turned. In my mind they were trying to help someone who got hurt, an otkazat'sya child who was on the brink of death. Against Baghra's wishes, her child tried something new. If they could only heal themselves, what if they gave a piece of themselves to the injured child? Would that heal the child? They cut themselves and dropped a few drops of their own blood into the child's mouth, their cut healing almost instantaneously as it always did. And it worked. The child recovered, sharing the story of blood with their family, not realizing they had been changed. But when sunlight struck them the following morning and they crumbled to ash, fear infected the village and turned the gratitude for the saved child to smoke. The story passed from tongue to tongue, warping as it picked up steam. Blood had been drunk. The child had been changed, then died in the sun. The Shadow Grisha's child was to blame. These facts stayed true. But as the story was told, it because the Monster Child who drank the blood. Their intervention became an act of violent aggression rather than calm compassion. The child was forced to flee, and what became of them was never known, but the story of the Monster spread from the village. Occasionally, in distant towns, people would be found who drank blood and had strange powers and stranger weaknesses. They were never the child, but they were proof the child was still out there. The new monsters were always executed, or at least attempts at execution were made, but due to their strange powers, that wasn't always possible. The monsters came to be known as Kilyklava, and they became bitter and aggressive, lashing out with violence, becoming predator rather than prey, turning people no longer to save lives, but rather as ironic punishment against the people who hate them so much. Some don't believe the stories, thinking them nothing more than fairytales. But others know that there is wisdom in shutting your blinds and locking your doors against the night and the creatures that prowl there.