People will occasionally complain about mandatory NPC shifts. But even if you don’t like it, you have to think: what about all the people who NPC for me?
When it is your turn to PC, you want the people being your monsters and villains to be entertaining and awesome, don’t you?
Well, they aren’t getting paid. They, like you, came to the game to enjoy themselves and have a good time. If you want them to be awesome, energetic NPCs, you have to return the favor.
No matter how much you don’t want to NPC (sometimes, I would rather shoot myself in the foot than play a cookie-cutter monster), you have to remember that the effort you put into it HAS the be equal to or better than what you want to receive!
It is all in the way you look at things. Sure, there is not much to interact with if you are a mindless creature, but ham it up! Have a good time making people stare at you in horror as you creep out from under their bed. Wait until they have made eye contact and slowly drool fake blood. Sneak up behind them and screech like a creature just let free from hell. Really get into your parts, and you will find that your NPC shift goes by quickly, and that you had a lot of fun, too. Then you get to smile later when people come up to you and thank you for making them wet their pants!
I will play a brainless flesh monster with as much gusto as I play a crazy fairy or a badass necromancer. I HATE being a cookie cutter, but since cookie cutters are a necessary part of the game, I will not be a half-assed cookie cutter. I will be the most terrifying brainless nightmare beast you have ever SEEN.
And I can only hope that the favor is returned when it is my turn to PC, and someone else’s’ turn to take their turn at being a creepy shadow monster.