Isn't that a bad end for Anastasia, actually? She has Serenity clinging right onto her.
She's going to die of severe poisoning.
She won't. People overestimate Serenity's poison. It even states in her profile that it can't kill a Servant unless she does something like kiss them three times in quick succession (prolonged or repeated contact with her mucous membrane). Otherwise it just causes them pain and weakens them.
If she could one-shot other Servants with just a touch she'd be considered a much better Servant lore-wise. As it stands, she's your typical Assassin class Servant. Good for killing enemy Masters and espionage, but not much else. In fact, lore-wise she's worse than your typical Assassin because she can easily kill her own Master by accident. Most Masters don't have Fujimaru's poison resistance and even breathing downwind of her is enough to kill most humans.
In fact, lore-wise she's worse than your typical Assassin because she can easily kill her own Master by accident. Most Masters don't have Fujimaru's poison resistance and even breathing downwind of her is enough to kill most humans.
This would make her an absolute shit assassin because she couldn't stealth anywhere. She would be a city-wrecker just by running around on a night with very little wind. It's utter nonsense. THEREFORE... In my FGO self-insert fanfic I verbally rammed common sense down the Throne of Heroes' throat until it relented and gave Serenity the ability to control her secretions, so she became usually relatively safe (if you can call being a spice cabinet of chemicals safe)