Spoilers below. GM's eyes only.
In book 2, in the top level of the Citadel cleansing, the characters encounter Janemine, who is disguised as Iomedae. My PCs stopped in their tracks when they saw her, and a paladin of Iomedae stepped up to receive a promised blessing. Others were suspicious but as there had been nothing to prove this was not Iomedae, they refrained from anything to stop the paladin.
So a kiss ensued and the paladin received the energy drain effect of one negative level and she failed the will save to resist the suggestion that she continue the kiss. The Energy Drain ability of the succubus specifies the will save DC to resist the suggestion, so it appears the usual rules given with the suggestion spell are voided: "Asking the creature to do some obviously harmful act automatically negates the effect of the spell." Since the drain energy effect is obviously harmful yet the will save is needed to resist, I take this to mean that the character will continue to try to allow another passionate kiss.
Now since that happened, one of the paladin's allies suspected evil hanky panky and ran forward and used the drag CM to pull the paladin away from the succubus in Iomedae's clothing. The succabus, still disguised as Iodmedae stepped up and used Vampiric Touch on the paladine, doing 24 points of damage.
My question: would the Vampiric Touch attack negate the suggestion already in place? The suggestion was not negated by allowing another harmful round of energy drain, so would getting attacked give her another saving throw, or having failed the initial save despite the obvious threat posed, would she continue to present herself for another passionate kiss?
I'm inclined to say that she continues to pursue the kiss, since this is the succubus's main offensive ability, mind control in various forms: charm, dominate person, etc. The party is strong enough to defeat the succubus without the paladin's help, so I think it will add to the drama if the paladin keeps putting herself at risk of another negative level.
But I wonder if there is some rule in some different place that would address this in a straightforward way. Suggestions?
I'd say the Paladin should remain under the effect of suggestion. "Obviously harmful", as I understand it, means "directly harmful". Paizo AP enemies are fond of ordering PCs to kneel before them, which, while very likely to result in harm, is not directly harmful.
The rule is to prevent making enemies walk off rooftops, imo.
I'd say the kiss 'disguises' the energy drain enough to not be seen as obviously harmful by the target, but the more direct attack of Vampiric Touch would break the effect.