Why aren't Tyranids and Necrons friends?

If Necrons want to kill every single creature in the galaxy, and Tyranids want to eat every living thing in the galaxy, why aren't they allies? It seems their interest coincide quite a lot.

>why aren't humans and spiders friend? Humans want to kill flies, and spiders want to eat flies. It seems that their interests coincide a lot

Necrons no longer want to kill everything in the galaxy. That's old fluff.

They're now trying to rebuild their empire while also finding a way to return to organic bodies, possibly transplanting their consciousness into an alien species to take them over. And they can't do that if everyone is eaten.

Tyranids might have just replaced the Eldar as the Necron's arch nemesis.

I suggest actually reading the fluff before you ask stupid questions

Well the nuance in their goals kind of sets them apart. Yes the Necrons you are talking about do want to make the Galaxy a lifeless shithole, but they want to make it their perfect lifeless shit hole with all the Doom and Gloom and ominous green Glowing shit. The Tyranids just want to eat everything and leave the Galaxy as a bunch of spinning rocks.

Then there's also the Fact that the Necrons are splintered and don't really know what they want. Yes, there are some who want to go all Terminator and kill everything, but then there are some like Trayzn, who just want to indulge in their Old man hobbies, some who want to keep life around, because they miss having fleshy bits and want to get them back, and even some who just want to be left alone, telling the rest of the Galaxy to fuck off so that they can continue griping about how the Galaxy has gone to shit in solitude.

If that's the case, why hasn't the whole galaxy united against tyranids?
-The Imperium hates the nids because they are xenos and eat their planets.
-The Necron hate the nids because their activities would harm them on the long run.
-The Eldar would hate them because of the same reasons, plus some species of nids ate soul stones.
-The Tau are scared shitless of them and would need any kind of help to cleanse their side of the galaxy of nids.
-Orks love killing tyrannids because they fight a lot.
-Hell, even CHAOS would win if tyrannids are wiped out, because without living things, there would be no worshipers.

It seems the perfect motive for a galactic ceasfire and just dedicate their whole resources against the space locusts.

maybe the moment any faction decides to let their guard down and trust another faction it gets utterly demolished / killed painfully / suffer eternal damnation, because that supposed "new ally" had betrayed them immediately?

Is this bait or are you retarded? Necrons want to live in and own the galaxy, they want to rule it and a lot of them want to return to flesh bodies by using current living life to figure out how to get back.

Tyranids want to strip every world bare and devourer EVERYTHING.

They don't share any goals

What this guy said. The factions of the galaxy don't really comprehend the Tyranid threat enough to drop their guard and work together.

Besides, the only factions that really stand a chance of stemming the Tyranid main fleet are the Necrons and Chaos Daemons (and even they may get fucked depending on how powerful the Shadow in the Warp becomes when the entire Tyranid species is there). Anyone else is just going to feed them more bio-mass and make them unstoppable, something the Silent King fears already has happened.

I would not take it granted that Necrons are unnomable.

>If Necrons want to kill every single creature in the galaxy
Oldcrons wanted that. Newcrons, by and large, want to get fleshy bodies back. Tyranids want to consume all biomass, then move onto the next galaxy of biomass.

Mutually exclusive goals.

What are Destroyer Cults?

Oh they can be nommed. Pyrovores are said to eat metal, and Tyranids consume parts of planets to use when making the chitin they protect their soldiers with. However, biomass is much more important, and the Necrons' ability to warp out means nomming them is hard and costly.

No, they cannot.

Forget to add why.

Necron living metal infects anyone who consumes with a nanoscarab plague which is self replicating nanomachines that will wreak havoc on the infected.

Also, according to "Word of the Silent King", Necrons are not fodder for the Hive Fleets. The Tyranids aren't interested in the Necrons. They will only attacked the Necrons if they are attacked first or if they are provoked.

Don't Hive Fleets tend to avoid Tomb Worlds as well?

It would seem if it were wholly up to the Tyranids, they'd never come in contact with Necrons.

They avoid active Tomb Worlds, yes.

Why don't everyone important just starts living on Tomb Worlds?

They add a theoretically infinite amount of biomass to the galaxy.

Makes cleaning a bit harder.

I want you to ask yourself that out loud, slowly.

Aww shit nigga, I fell for the bait.

because tyranids were created by the old ones to devour all life to stop the necrons, who were powering themselves by absorbing the energy from the beings a long time ago.

That's never been confirmed. It's about as valid as the "Tyranids are running from something" theory.

Old fluff states they are almost as old as the universe itself and travel from galaxy to galaxy to gather new DNA and survive. Recent fluff is just very vague