I asked this on another forum and weirdly got bombarded with people telling me I was humanising my dogs.
I was watching Erik with Kivi the other day and Erik was mugging Kivi for a ball, all growly and bitey. Kivi didn't like it, so he took to dumping the ball and pouncing on Erik and pinning him down. I let this happen because Erik needs to learn that he can't walk all over Kivi ALL the time. Anyway, Erik very much didn't like this and when struggling and growling didn't gain him release, he struggled and growled more and bit Kivi's foot. I am guessing it hurt, because Kivi made some whiney noises and squished Erik.
Anyway, I thought this was all very interesting and made a mental note that Erik might get right worked up if he doesn't like something, and decided in my mind that I would be careful to set him up for success and avoid being on the receiving end of an Erik growly fest. Erik is a far cry from the puppy my mother had once that was downright aggressive and would try to hurt you if he didn't like something, but I saw the potential in Erik for escalation and thought it might be smart to keep that in mind and avoid putting Erik in a situation where he might try that on with me. This does not mean I'm going to let Erik get away with things so he doesn't throw a tantrum. It means Erik will be handled a lot and gradually introduced to things he doesn't like with lots of desensitising and lots of positive training so that he learns a) that things he doesn't like aren't all that bad after all and b) people don't do very mean things to him that require growl fests and tantrums. I think inevitably he will throw a tantrum - he already barks at me if I have the clicker out and haven't given him a chance to get a click in the last 5 seconds - and I intend to handle it by pretending it isn't happening. He can holler all he likes, but it won't change what I'm doing and if he's trying to be demanding I might just walk away and come back when he's feeling more civil.
I quite like Erik's spunk, but I don't really want to find myself on one of those slippery slopes where I have to hold a puppy down because if I don't it will bite me hard. So lots of desensitisation. I'm currently handling Erik a lot, picking him up and rolling him over and tickling his belly, trying to gradually increase his tolerance to being restrained without provoking him.
I'm curious to know how other people approach puppies that sometimes get stroppy. Kivi never got stroppy. He was a cry baby instead.