There are already too many Celestials for his liking. There's no way he will allow the god of fate to muddy the waters with Stelios already in the mix. He will keep him away from everything.
He said to himself, "But he is right. I need help."
A demon king is a threat to him and more than enough threat to be the doom of the mortal realm. He has been fighting back the enemies from all sides but he is only one Celestial. The help of another Celestial will be useful and might help to turn the situation.
As much as he loathes this current state of things, he has to admit that the situation is dire. It is a situation in which 1 Celestial will not be enough. Especially with Helios still around to contend with.
"Let's hope it is not too late." He said as he sent a request for communication to Stelios.
There's nothing safe and easy that he can do against a demon king rampaging in the mortal realm. He might have had a chance before his son was butchered for a ritual, but now, he is helpless. There's something that he has been hesitating on which he could have used earlier if he knew about the full threat of the demons. Now he doesn't have a choice. He has to do it and he needs Stelios' help to make it work for sure.
So he decided to have a sincere talk with the true Celestial god of the sun. It is obvious now that Stelios is not with Helios. Even if they were acting together in the past, there's no way a Celestial will be okay with the complete elimination of their livelihood in the mortal realm. He should be able to take advantage of the rift between Stelios and Helios to his benefit. Maybe he might learn some secrets about their plans.
He chatted up Stelios immediately. Stelios accepted his request for communication. A connection formed between them but Stelios only allowed it to be an audio communication and he refused to talk. He simply listened to the Celestial Supreme talk. The Celestial Supreme promised a ceasefire between them with a contract that will see to its effect if Stelios will help him. He is willing to make an oath not to try and kill Stelios anymore unless he has a reason outside of his need to eliminate other Celestials.
He truly is desperate because he didn't insist on non-interference from Stelios as a Celestial. It is that same non-interference that is preventing the Celestial god of fate from joining in this war. He needs Stelios to get involved in the war plus the Sun god is not a threat to him unlike the god of fate that is untouchable.
The two of them formed a verbal oath enforced by their domain and authority.
He asked the sun god after they had formed their oath. "When can you get ready to assist me?"
The sun god replied with an obviously weak voice, "Fine, I'll help. But you must bring all my divine lords to my divine kingdom. I prefer if you do it against their will. Bind them up and deliver them to me. I'll be waiting."
Then he cut off the communication line.
The Celestial Supreme was perplexed about why Stelios is so weak. He could sense the weakness from the divine fluctuations of the other end of the communication line. He isn't perplexed about the request though. If Stelios is weak and in dire need of help, it is normal for him to want to consume his divine lords. He has a lot of them because of his long history as a god so they should heal him to a significant extent.
It also means that Stelios is nearly helpless that he can't defeat his divine lords on his own. It is a good opportunity to try and take him out but the Celestial Supreme chose not to take advantage of him in these trying times. He can't even if he wants to, he already signed a contract not to try and kill Stelios or the sun god wouldn't have been vulnerable to him.
They agreed to help each other in eliminating the demon king. Stelios will help him to the best of his abilities while he will get Stelios his divine lords. He can't attack his ally and it is also a good thing that his ally is weak.
"Stelios won't be a threat to me for a long time to come. Maybe I should keep him around after this is over." He said to himself after sending his angels to kidnap the divine lord and bring them to his ailing partner.
Stelios is the perfect ally. His condition makes him useful and also too weak to be a threat. It made him begin to consider his ban on Celestials. Maybe he will keep the weak ones alive and kill the troublesome ones that can threaten his power. He can also use the Celestials to kill the god of fate. The fact that he couldn't do anything to the god of fate doesn't mean that others will be helpless.
STELIOS POV
Stelios received his divine lords and consumed them for their Godhood. Their Godhood came from him and is the most compatible nourishment for his injuries. Divine lords aren't gods. They are children of gods who were granted a Godhood that has been refined by their divine parent. The godhood they receive elevates their existence but they don't become gods because there's a god in that domain already.
The presence of Stelios in the domain of the sun is stopping the god fire of his divine lords from lighting up. They will get their god fire and become gods when the domain becomes free of a god. Of course, they have to kill their other competitors until the last man stands. So it is normal for the divine lords of a god to be hostile towards each other but it is not so for those of the sun god.
The divine lords of the sun god have nothing to fight for so they are amicable with each other. They also never thought that their father could be a threat to them. It turned out that they were wrong.