The way I understand this is:
- Gab doesn't mediate for his own sake. He does it for Emma's sake. Nael can't possibly save her, other than perhaps turning her into a Dark One which isn't the goal.
- Zero doesn't really do anything wrong. Companions killing each others for power is a fairly natural process. So inquiring about this is to be expected and the only reason he stayed his hand was because he had to deal with Nael's Companion. Also Gab is known to favor diplomatic resolutions.
I mean yeah, of course Nael doesnt give a shit about Emma but they doesnt know about that. From their perspective Nael's companion appears and tells them to fuck off. This should indicate for them that it is against Nael's interrest which (should) make it a way to risky move.
Its not like Nael cares particulary about the rules of the bond or the dark ones, if she gets pissed the other one gets deleted no matter the rules. Its just kinda unlucky for Zero.
- Dark Ones aren't privy to Nael's true nature and we've seen that even Gab can faulter against overwhelming odds. He didn't beat Tessa conventionally and we don't really know if other Dark Ones understood the extend of what happened. So perhaps Zero/Dia think that if Zero claims Emma's power, he may even have a chance against Nael. After all, Tessa thought she had one.
Completly disagree with all of this strongly. Nael's true nature doesnt really matter, all that matters is that her power is so overwhelming that its uncomprehensible for the other dark ones and even primordials.
Gab didnt faulter, he didnt took the fight serious for a single second and just toyed with matt nonstop. And come on, imagine how rare it has to be for gab to really showcase a amount of his power so why not?
Tessah didnt thought for a second that she could win, she just went along with matt's orders and insanity (which get enhanced for her), the only "problem" was that tessah's true form damages reality and therefore Nael had to intervene and delete her.
What really happens when Nael (gab) gets enraged is shown in the first dead end with Matt and (a still sane) Tessah. After Tessah killed Noel, Nael just deletes her in a second after her arrival and does the same over and over for every 10000 years tessah revives.
There was no fight and nothing has changed. The moment Nael decides to kill Tessah, Tessah is gone.
If Gab fails to persuade Zero though, Zero makes a mistake.
Dia thinks that Gab is abandoned by Nael. She obviously doesn't know the extend of their relationship.
So Zero kills Gab, and Nael resets the whole world.
If Zero had just killed Emma and left Gab alone, I don't think Nael would/could do anything at all to help the situation.
Yeah thats why i tried to say, attacking Gab is a way too big risk for them, no matter if they are SURE that he is Nael's companion at the time. Dio knows Nael since forever and knows about her .. being easy to enrage and what happens to the people who enrage her.
But yeah if they would have just killed Emma, Nael wouldnt have given a fuck, thats true, they just dont know that.
I really have to play the world reset path, didnt saw that yet, i imagine it is a dead end?
Edit: Thats a Nael vs. Tessah "fight"