Could we please not base this thread on one of the many badly thought out additions to the game of late? I'd call it the worst but that would be overlooking oh so much from the supplement codices.
They're zealous, not stupid. This isn't an alliance as in ''yay we're friends now,'' it's more a non aggression pact, when there are greater enemies to deal with. Eldar are well known for temporary alliances, and Tau will work with anyone, more or less. So as desperate allies go, they make sense. Plus the chart is as much for gameplay as lore.
First, the chart is all for gameplay, and very little for lore. Lore-wise, the only factions to make buddy-buddy are the Eldar and Tau, any human faction (and even that's sometimes a stretch,) and maybe the Imperial Guard and Tau. Oh, and the Blood Angels and Necrons. But I don't see how the Sisters could make a Non-aggression pact with the Eldar, considering if an Eldar tried to negotiate with them they'd kill it as soon as they saw it. Maybe if the Eldar kept out of their way they'd not actively try to fight them, especially if there was Chaos right there. But is it really any kind of alliance or pact if only one side is even aware of it?
The whole point of the allies matrix (and warhammer 40k in general) is the ability for each individual player to forge his own narrative. If i have a chao army allied with imperial guard, then (although I'm using the imperial guard codex) they are no longer imperial guard, rather planetary defenders who have turned from the emperor and decided to side with chaos. SIMILARLY, if i have a chaos army allied with tau, I CAN MAKE MY OWN NARRATIVE that states that "these tau were once strong believers in the greater good, but after their home world was destroyed by an imperial fleet due to the failure of the tau empire to send reinforcements, they turned to the immense power of chaos and became cultist-like renegades" nothing in the tau codex states that tau can't be corrupted, and nothing in the chaos codex states that it has no interest in tau. thats why warhammer doesn't give you all of the information, it wants you to fill in the blanks on your own
Pardon me, but isn't that a point in favour of the Sisters of Battle opposing an alliance with Chaos? They are a group of ten thousand year old traitors who stabbed the very god they worship in the back and are known for killing and turning on one another just as much as the enemy. That's not someone to make any kind of pact with. The same goes with the eldar. Even getting past the problem of xenophobia, many Imperial factions tend to distrust them thanks to their ability to use humanity as a kind of meat shield or manipulate them to take the brunt of certain assaults. Two of the major wars for Armageddon were caused by them directing the orks to that world after all. If anything the smarter option is not to trust either. Indeed. Unfortunately that betrayal was nothing in comparison to what was done to many others. Especially the Iron Hands.
I mean... The chart seems to be saying it's possible for IG and Tau to be allies of convenience, just the same as it's possible for IG and Chaos to do the same. I think that's just silly. You can tell me it's up for interpretation or "blank filling," but frankly I don't see why Chaos isn't as red-across the board as the 'Nids. I see the chart as a delineation of "which factions can be allied for big table-top games", not accurate fodder to write fanfiction on.
I disagree. You're taking the chart for something it isn't. It is not trying to account for race wide alliances. It is accounting for possible alliances which may occur, in certain circumstances. The general outlook of a race doesn't account for each and every single commander, either. So listing Chaos as allies with IG is fine, because in certain circumstances the IG will ally with Chaos (when they turn traitor). That's not to say that some of the things on there aren't a bit meh, or that the chart couldn't have been designed better. But equally you can't outright dismiss the idea of temporary alliances because no race is too proud/stupid to simply die when there are possible allies at their doorstep. Most take help where they can, if their need is dire. I..what? Alliance with Chaos? Yes. That's why they aren't battle brothers, but desperate allies. They will aid one another if the need is absolutely dire, such as a full scale chaos invasion. Desperate allies even includes a rule for distrust.. IG can very much be allies with Chaos and Tau. Traitor guard and Gue'vesa, respectively, prove such.
since, according to games workshop, the only true true cannon is in the codices, there isn't a better place to get your information from. warhammer has been around for a while, unfortunately things have to change (thanks tzeentch ) and one of those new changes was met with anger. but this is the new warhammer cannon, and theres nothing you can argue against that
Let me put it this way for you. There's a very good reason that most of the collective WH40k fandom groaned when they saw Blood Angel Chapter Master Dante had allied, temporarily, with the Necrons. If the IG aligned with the Chaos and turned traitor, they wouldn't be IG anymore. They'd be heretics, traitors, the Lost and the Damned. They'd be something other than the collective human military arm, which falls under the umbrella title IG, because after the fight they wouldn't report back to the Administratum, they'd go do whatever it was traitors and Chaos did. They'd probably even themselves deny being IG any longer. So that explanation is invalid. In terms of the Tau, they might ally with Chaos against, say, 'Nids, if it served the Greater Good, but they'd do that with anything. So yeah, the chart is right there. But on the whole, the chart is wonky and a lot of nonsense. The only faction it got completely right was Tyranids.