One of the gameplay elements I've been struggling with for a while is how to unobtrusively display important changes in, or interactions between, monster girls. For example, if you instruct two monsters to have sex, one might reject the other. Fine. The problem is that there is no way for the player to know what went wrong. Or if you tell a monster to do something, and they simply do not have the energy to perform the task, again same problem.
I'm implementing a system which will display icons on a speech bubble when these changes/interactions occur. Monsters recovering Hunger or HP, for example would print an appropriate icon to this box.
Other hidden features such as stat passing could also be displayed through this system.