"Let's swear the oath and form the coalition. We have chosen our side. We must not lose." WRATH said to the others.
It might seem foolish for GREED to give up on the coalition since siding with the coalition will give it the assurance of a reward. But it isn't foolish because it is the only demon God that isn't part of the coalition. That means if the realm tree loses in the era of conquest, it will be the only demon God in the running to become the world-ender. It will certainly become a world-ender even without doing anything to sabotage the realm tree.
The others won't be able to compete with it because of the realm Lord's deal. The realm lord didn't need to offer them that deal for demons to help the realm. Everyone and anyone is allowed to join in to help the realm and the realm lord will reward them if their contributions reach a certain level.
The realm lord is rich but he can't afford to reward everyone for helping. They have to make a significant amount of contribution before they can be rewarded. That means being rewarded is uncertain if you help the realm tree. You have to make a lot of contributions. But the realm lord offered them the deal which will make it certain that they get a reward. In exchange, they can't act against the realm tree.
Since every other demon God is accepting the deal, only GREED can act against the realm tree and reap the benefits if the realm tree loses. But that's only if the realm tree loses. If the realm tree wins, then GREED is still not a fool because it can still earn rewards if it makes enough contributions to the realm tree. Talk about eating your cake and having it.
If by chance the realm tree loses, then the 9 demon gods will get nothing and will be the foolish ones. So in a way, the demon gods have chosen sides. They will act either for victory or defeat of the realm tree. It is all because the realm lord coerced them to choose sides instead of working on both sides.
Those on the side of victory get certainty of reward but they can also lose everything and get nothing if the realm tree loses. This will ensure that they do their best to make sure the realm tree wins in the era of conquest.
WRATH said to the demon kings, "We have all decided to swear the oath. All except for GREED. We will not protect you from GREED. But he won't force you to do anything related to the coalition either. It will be just like the past. You will all have to find a way to protect yourself. I will go first."
"I WRATH swear upon my sin that I will not attack or harm a demon king or demon lord that joins the coalition without being provoked or without it being warranted. I might harm a demon king or demon lord but it will not be intentional, malicious, or with the motive to cause harm and it will not be without a valid reason. I swear this upon my sin with the will of the abyss as the witness, judge, and enforcer."
An oath sworn upon their sin is very powerful and binding. If broken, it will lead to serious damage to their sin. The sin is the foundation of their existence. The smallest damage that they will incur is a fracture. They can't die but the fracture will be very debilitating. It can be likened to someone breaking every bone in their body and still being alive. The fracture can be healed but it will be very expensive to do so. So it had better be worth it to break the oath.
That is just when the oath is sworn on its own. The consequences of breaking an Oath become even more debilitating when you add the will of the abyss as the witness, judge, and enforcer. That fracture created if the oath is broken will never heal because the abyss will constantly open it and try to expand it.
The best situation is for the fracture to remain for as long as the demon God remains a demon. That is most likely forever since there are only two highly unlikely ways for a demon God to stop being a demon. The first is to become a world-ender which is very difficult in a normal situation. It becomes nearly impossible to achieve with the fractures.
The second is to die which is very difficult. Demon gods can be killed, but you will need a very powerful supreme law for that to be achieved. But that wouldn't solve the problem of the fracture. Death is certainly worse than large painful cracks in their existence.
The worst situation in case the oath is broken is for the fracture to eventually kill the demon god. So WRATH was very serious with its oath. It showed its sincerity to work with the demon kings and demon lords.
The other demon gods took turns swearing the oath. Aeternus watched this calmly. He didn't let his unhappiness show. GREED didn't join so he still has one very powerful enemy out there. It is an enemy that he has provoked several times too.
He also isn't happy because he has to join this coalition to get any safety from the other demon gods. He doesn't know exactly what the coalition is about so he is wary of it. He is doubly wary of it because it has something to do with the realm lord. Anything that has something to do with the realm lord is always tricky.
Unfortunately, WRATH swore to stay away from only those who joined the coalition. It is a threat in and of itself. The oath shows its sincerity but that clause shows its deviousness too. Now if Aeternus doesn't swear loyalty and form the coalition, he will have more than one demon god knocking on his door.