Hi! What unresolved plot thread bothers you the most?
The Yeerk Peace Movement!
I’m probably saying that at least partially because #29 is my favorite Animorphs book of all time (closely tied with #26, #38, #51, and #54, all of which are also my favorite Animorphs book of all time, and I never said I was a rational person, just that I really like Animorphs). But I also think that Applegate is doing something really important, and really cool, by having the enemy forces have a resistance force within their ranks. So much of Animorphs is about breaking the black-and-white thinking that other conflicts (and, frankly, other children’s SF) so easily fall into, and the YPM is a huge part of that motif.
Not only that, but the plot potential around the YPM is nearly infinite. I speculated here about how the YPM could end up being the dominant force for the entire Yeerk Empire, and here about its potential for infiltration and sabotage. The YPM could help the Animorphs negotiate a better treaty with the andalites. The YPM could pass information to the resistance, but also build out the resistance within the Empire itself. The tiny handful of appearances they get in the later books — staging a protest in #43, saving Jake’s life in #50 — don’t showcase their sheer coolness potential.
When speculating about Animorphs movies, I think I talked myself into my favorite idea for the YPM: that they could simply replace the chee in the final battle. Instead of the whole hologram-thing, the Animorphs could have a yeerk ally ride inside Cassie (with her consent, of course) in order to fool the Gleet Biofilters. If they set up a bunch of YPM-yeerks among Visser Three’s retinue, they could take the Pool ship as bloodlessly as possible. It could work, and it could reinforce the series’ motif of there being no good or bad peoples, only good or bad actions on the part of individuals.
Also, think about the degree of emotional impact if it’s a YPM yeerk, not a chee, who drains the Pool ship’s guns. Imagine if that moment isn’t about Erek’s passive-aggressive tit-for-tat “you made me be here, so I’m going to choose to interpret my nonviolence programming in a way that gets your cousin killed” attitude. Imagine how heartbreaking it would instead be if Illim or someone does it because “I thought we had an alliance, but you just murdered 17,000 of my people. So I don’t give a fuck what it costs you, I’m making sure that you don’t have the chance to kill another Blade ship’s worth of my brethren.” That would be a spectacular case of Jake’s homicidality having immediate and horrific consequences for him and for his entire team.