From what others have written on this site, Butcher has said that the demons that make the White Court vampires and the White Court mantles don't mix, which lead some to conclude that Dresden and Lara are unlikely to consummate their arranged relationship. But in the released chapters of Twelve Months, Mab is pushing hard for Harry to sleep with Lara ASAP.
And given the apparent ground rule from those chapters that Lara can't use her Whampire powers on Dresden - and she's suppressing her demon for the dates - that consummation would occur while the demon is basically unaware/asleep/unconscious/whatever.
What Mab's play here? Does Dresden or Winter gain some level of control over Lara or her demon if that consummation occurs while the demon is incapacitated? Or is Mab counting on Lara conceiving a child with Harry? There must be some advantage that accrues to Dresden or Winter for Mab to be that interested in Harry and Lara sleeping together at the earliest possible moment.
I think Lara is simply being very-careful to keep her Hunger "satiated" when she meets with Harry. It isn't "incapacitated," just much,
much easier for Lara to keep under control.
I'm unclear why Mab is pushing for this; as you say, we've got WoJ that the WK-mantle issues around sex/violence and the sexy Whamp-mantle play together in uncontrollable ways.
I suspect Mab's agenda is either:
- to put extra pressure on Harry to find another solution
- to get Lara killed, by way of triggering Harry's Mantle
I suspect she has contingency plans for either alternative.
I don't feel I understand Mab's "big picture" in this, however!