While the name of this spell is sharesister, it works equally well on male or female creatures—both targets of the spell must simply be of the same gender.
When you deliver the spell, you receive a negative level for the duration of the spell, and the other target receives a +1 insight bonus to her caster level and a +1 insight bonus to the save DCs of all of her spells. At 11th level, you can opt to take four negative levels to grant a +2 insight bonus to the other target’s caster level and spell save DCs if you wish, while at 17th level you can take 6 negative levels to increase the insight bonus to +3. Any effect that removes or prevents the negative level immediately ends the sharesister spell. Negative levels received from the spell vanish as soon as this spell effect ends. Negative levels from multiple castings of this spell stack.
Pathfinder Campaign Setting: Pathfinder Society Field Guide. © 2011, Paizo Publishing, LLC. Authors: Erik Mona, Mark Moreland, Russ Taylor, and Larry Wilhelm.