I remember in some random books, like the leeran one, that they hinted at the yeerks infiltrating into the andalite world. Traitors among the andalites on the Leeran war, and visser 3 turning into a bird native to Andal. Did that ever go anywhere?
No, not quite. *shakes fists at sky in frustrated rage because that could’ve been so cool*
We get brief mentions from Alloran in #8 and Andalite Chronicles that there are traitor andalites. HOWEVER, since this is War-Prince-of-Imperialism Alloran-Semitur-Hardass speaking, it’s entirely possible that his definition of “traitor” is not that of normal people.
The most definitive proof we see of andalites actually working for yeerks is in #18, when the captain (and some of the crew presumably) of the Asculan deliberately tries to sabotage the mission on Leeran. They’re killed in the resultant explosion, and that’s the last we get of andalites working for yeerks.
There’s also the whole thread in #38, #46, and #51 - #54 of the Andalite War Council being willing to sacrifice most or all of humanity in order to contain the yeerks on Earth. Again, it depends on your definition of “traitor,” and even post-Esplin Alloran probably wouldn’t consider that treason, but Ax most definitely considers it a betrayal of all the andalites claim to stand for.
[Image ID: Screenshot from #52 that says “The orders would say to quarantine. But what everyone would understand is that a quarantine would be impossible to sustain. To enforce a quarantine, the Andalite fleet would be forced to engage. And once they engaged, they would annihilate the planet and every living thing on it. Yeerk and human. Quarantine was the first step toward genocide.”]
Again, it depends on the definition of “treason” we’re working with. But the nasty underbelly of the War Council, one it works hard to conceal from the Andalite Electorate, could definitely count.
Is it the super-interesting political intrigue with spies and counterspies between andalite and yeerk forces we get hinted at in #8 and #18? Nah. But it’s definitely something, and the turn the andalites take in the late series — toward being even bigger antagonists than the yeerks — gets foreshadowed by those early moments in the series.