It really depends on the enemy. For example, prisoners will opt for having Karryn give them handjobs - when cock desire passes 50. Prison guards generally will also follow this pattern. When Pussy desire passes 85, goblins will grab Karryn and start eating her pussy. This is the only way goblins can initiate sex during a battle. Sex of any kind will not happen until the particular desire is over 100, and Cock desire is at least 85. Karryn will not be fucked in her pussy unless both desires are at the required levels, she's been sufficiently stripped (unless you have a certain passive), and her pussy is wet. Also, each enemy only has a specific set of moves they can use. Nerds won't perform cunnilingus or sexual counter attacks, Thugs won't go for anal, slimes won't initiate sex of any kind unless anal desire is over 100.
Some sexual positions require a certain condition to be in place. For example, to get the sex counter attack, try getting her pussy desire over 100 and cock desire to 85, then while her pussy is wet and she's basically naked, kick a thug - instant sex. If your anal desire is over 100 at that time, and there's a rogue or a prisoner in the battle, Karryn's getting DP'd.
