I think you're right. Serini probably hit Roy with the same poison that she used against O-chul and Lien, given that he's the same sort of target, and based on her comments after the pair woke up, it might not be a poison that does ability damage, instead just knocking them out and keeping them knocked out for a while. Obviously it'd be something stronger than the poisons listed on this chart, at least in terms of Save DC, but something like Drow Poison listed there would be sensible for Serini to have been using.
I mean, Roy might need a smack in the face to wake him up after the poison keeping him asleep is removed, but that'd be it if its the same stuff that hit V.
EDIT: I think you're looking at the wrong battle. First panel in 1244 shows Elan Neutralizing Poison on V, who is asleep from one of Serini's induced poisons.