notice how the animorphs lives didn't really suck until after book 19. the new guy tries to kill everybody,rachael starts to realize she's a sociopath, (which is proven in the separation),tobias loses more of his grip on humanity then gets tortured, marco comes to term that his mom may need to die (he almost pushes her off a cliff) then is held back and sees her be shot and fall, ax is torn when the new andalites arrive on earth and doesn't know what to do,and jake has to shoulder the crushing responsability after he lost his family.
before this it was mostly, the yeerks are trying to do something, we go in and stop it,visser three shows us a new morph,escape with minor injuries. next mission.