We currently have the following neutrals:
Reaper(should stay immune, NK)
Possessor(same as above, NK)
Mercenary(already fully convertible)
Alchemist
Fool
Scorned
Here is my suggestion:
Fool and Scorned are immune to conversion if they complete their goal.
As long as the did not, they can be converted into the Cult, but not into the Unseen
As a compensation for converting neutrals, they would keep their Trollbox day ability upon conversion(like Royal Blood, which is kept upon conversion).
Alchemist would be convertible for both, because the acceptance of an alch working for BD can be horrible for Unseen(3xNight immune+2 kills/unlimited heals); all examples I can recollect so far were horribly onesided for BD. Alchemist, as a compensation for converting a neutral, would keep Coagulate and Stoneskin Potion on them.
Its Unseen class would be:
Poison Brewer (Unseen Killing)
Passive:Coagulate
Day Ability 1: Stoneskin Potion(No change)
Day Ability 2: Harvest Nightshade(1 use) Give the assassin one more usage of Nightshade, at the end of the day.
Night Ability 1:Poisoned medicine(unlimited uses):Heal someone. This also heals bleeding. If they are healed, they will die of a silent poison two nights later. That poison can only be detected and healed the following night.
Night Ability 2:Suspicious Potion(unlimited uses): You will poison someone with a dubious, potent poison, killing them next night by poison. Any guard(Knight, Guards of the King, Mercenary) kill you without being killed themselves, and prevent poisoning. Any other visitor will see you.