I don't really think that an Etheral's mind can be that easily corrupted. So instead how about the idea of the week minded soldiers being corrupted by the power of chaos and overthrowing the Etheral.
:crazy:

 

Seeing as how they are 100% psionically dead, I don't think chaos has any hold over them, being warp entities (or interest, for that matter, since tau thoughts have no presence in the warp)

 

Being psionically dead as you say will just leave the mind open to an invasion. Plus any near by sorcerer has an even better chance of suceseeding.

 

Nope Psionically dead means their minds are compleatly and utterly shut to the warp and all its effects.

 

Yep. Tau are immune to corruption by chaos. That's why supposedly the eldar designed the ethereal caste to shape them into an awesome race. That fluff feels stuck on though just to make them GRIMNDARK.

 

How does it happen? It doesn't.

Having said that, if you want to model your army in a Chaos fashion go for it, nothing is stopping you, but in game, they're still Tau. Don't think anybody is going to play an army with railguns and power weapons.

 

Wow, what is with all of the Chaos Tau people here? Eesh, ok, let me go over it again...

Tau have a minuscule Warp signature, so small that it is virtually impossible to see. Comparing a Tau Warp signature to a Humans would be like comparing the radar cross section of a butterfly to a Boeing 747. A single Psyker could possibly outshine the entirety of the Tau race. As such, the Tau provide very little interest for Daemons anyways, and the Daemons can't even whisper to them anyways.

For those who want Chaos Tau, there is hope. 1 Tau in their entire race is known to have been influenced by Chaos, that Tau being Shas'La Kais. His mind was affected due to an extremely powerful local Chaos presence, the psychological shock of seeing an Ethereal die and the emotional trauma of his world essentially falling apart. Even with all of that, he simply went insane and provided no way for Chaos to get much further.

There is also speculation that Farsight may be influenced by Chaos, most likely Khorne. I did not say controlled, possessed, anything like that. At the most, there may be whispers heard by an emotionally distraught Tau who feels betrayed by his Empire and who lacks the calming pheromones of the Ethereals. This is all speculation though, and it is just as likely that Farsight is influenced by the Necrons, the Old Ones, the Eldar or is even just batshit crazy without any of them getting involved.

As for the Tau being weak minded, nothing is farther from the truth. They're pretty much brainwashed to follow the Greater Good and the Ethereals from birth, and your average Shas has been training to be a soldier (Complete with further brainwashing and indoctrinations) for the last 15 or so years. The ethereals themselves seem almost completely impervious to outside influences, and have such steely personalities that they have the same Fearless abilities as a Space Marine Chaplain.

Hope that has given all of you a little insight to chew on.

 

For those who want Chaos Tau, there is hope. 1 Tau in their entire race is known to have been influenced by Chaos, that Tau being Shas'La Kais. His mind was affected due to an extremely powerful local Chaos presence, the psychological shock of seeing an Ethereal die and the emotional trauma of his world essentially falling apart. Even with all of that, he simply went insane and provided no way for Chaos to get much further.

With that in mind, remember that the game Firewarrior was really full of crap for the most part. Thus I'd take that example with several buckets of salt.

Because when we get down to it, the game is full of glaring unrealities like, oh, just say a single Firewarrior with magically regenerating armour, photon grenades that blow people to shit and lasguns that are actually comparable to his pulse rifle.

Then we see that him assault/capture/blow the shit out of several Imperial trenches and installations on his own, cause mass destruction during a counter-boarding action on an imperial navy vessel on his own, gun down Space Marines and their Chaos cousins by the dozens on his own, and generally break just about every fundamental rule he can get his little blue bastardising hands on...

I'm honestly surprised that we didn't encounter any female Space Marines in the game, but I suppose Kuju had to draw the line and stop raping the 40k universe for cash at some point.

Thus rather than labeling Kias as the "Sole known Tau in the entire race to be influenced by Chaos", I'd change that statement to Kias being the "Sole known Tau in the entire race to be influenced by the game developer company formally known as Kuju, now another nameless company that's been damned to the nine hells."

 

Usually when Kais gets mentioned, it's referring to the book
His exploits are a bit more acceptable there ... and at times hilarious.

"Take this Daemon Prince ... Crap, out of ammo. Well, I can just beat you with my rifle!!! Oh, you cut off my arm, shit ... um, I know, I'll beat you up with my HELMET!!!"

*Enter 3 Battlesuits which blast the crap out the Daemon Prince*

"Yeah, I showed you, fear the mighty helmet of the Tau!! ... I think I'll pass out now."

He's not so super-hero in the book, he's just clever and lucky. For example, in the book, he tricks a rampaging dreadnaught into killing itself (getting it to run off a high ledge), where in the game, you find a dread that will glitch if you stand in the right place, allowing you to then walk up to it and cut it up with your knife while it stands there confused.

Game = Rape
Book = Gentle Spooning

 

I saw a while back someone said that Chaos Tau would be most likely to occur with Tzeentch turning the Greater Good into his own plans. I can imagine Tau with mutations, as the castes are all different mutants from the original Tau, even physic Tau to improve grip over them.

 

The Tau can be like heretics in a way in that they aren't controlled but a volenteer to chaos. The tau's campaign can be a way to secretly taint a world taken by the empire. Like thomas2 had said. Yeh no psicological possession but the taint can still be there.