So my immediate thought given this context would be to make the new strain/miracle drug/whatever be something that combats the existing evil virus as a counteragent. So it would provide some amount of resistance/immunity to it, but i like the idea of a (probably unknown) drawback. Something like cordyceps maybe that slowly takes over and/or controls the person like you mentioned.
This could easily be told to the players through the NPC you mentioned who has control of the new strain/drug; he can slowly become more erratic/out of control, and his actions can start to get more suspect (along with any potential physical signs).
So basic idea for a campaign would be:
- Players run into NPC that has new miracle drug that provides resistance/immunity to super evil virus
- NPC is being hunted by the AI because of it
- Players try to protect and help NPC get to somewhere safe to begin process of creating/manufacturing/growing new drug at scale (current supply must be protected because it’s so low, so player’s can’t have any, but they know the NPC has tried it on himself)
- Over their time with the NPC, his motivation and actions begin to turn more sinister as the effects of the drug set in
- Player’s need to eventually make a choice as to if the current situation with the virus or the new threat from the miracle drug is the lesser evil.
Yeah, we have a set day and time, and will only reconsider if 2+ people are missing