Aeternus isn't actually feeling carefree. He is alarmed, very alarmed. He is proud but he is not foolish. Danger has to be taken seriously, especially unknown danger.
What he said earlier was all true. The demon lord had tried to con him into making a deal he wouldn't have considered. He might be in danger but making a deal with the demon lord is walking into another dangerous situation willingly. He would take an unknown danger over the known danger that is the demon lord anytime. After all, what could be more dangerous than the demon lord in the abyss plane?
A demon king is more dangerous than a demon Lord but that's another situation entirely, he doesn't stand a chance in that situation. Not even if he gets the help of a demon Lord unless the two of them are pranking him. So now that he has eliminated the obvious, this leaves the high-rank demons or the demon nobles as the enemies that could threaten him.
He has offended two demon nobles last he was aware of, maybe more that he isn't aware of. Then there's the chaos he started in the domain of high-rank demons. Change is either pleasant or unpleasant. It usually isn't pleasant for those that were benefiting from the former situation before the change. There must be some demons that his activities have rubbed the wrong way.
Try as he might, he couldn't figure out who would be after him. This is the abyss, anyone can be ought to get you. There doesn't need for there to be grievances for two demons to try and kill each other. Demons have been known to join a free-for-all without knowing what caused the fight in the first place.
The only two things he could ascertain is that the threat has to be highly dangerous and capable of taking his life. Or the demon lord could be lying. Any one of them is highly likely because he could tell that the demon lord doesn't want him to die. Her desire to see him alive is not because she is kind, she obviously has an ulterior motive.
It doesn't take a genius to figure out that a demon offering aid and assistance has an ulterior motive. Her motive is highly obvious to him too, so he can be sure that she doesn't want him to die, yet. He continued rushing to the border as his mind went through various likely scenarios. Only one thing is certain, he will be safe when he reaches the domain of mid ranks.
In the domain of Demon Nobles. In The Throne room of Salazar. Before The Demon Lord Approached Aeternus To Warn Him.
Salazar the Balde of destruction, was calm as information about Aeternus was read to him. Aeternus killed Alkazhi, then he killed 14 high-rank demons. He went on to bring down a fortress on his own. It is an unheard-of feat but the Ominous Reaper succeeded in doing it all alone.
The owner of the fortress failed in escaping and died to him. His 8 allies that came to take advantage of the situation got their ass handed to them. Aeternus began his reign of terror as he brought down fortress after fortress and he killed 50 high-rank demons. Now high rank demons are always running scared when they see the Ominous Reaper.
The more Salazar heard, the calmer he got and the chillier the air got. The air was practically frigid by the time the 10th high-rank commander was done. No one breathed or moved. They had their heads bowed while Salazar simmered and brooded. Then Salazar exhaled and the tension in the air relaxed. He had made his decision.
"So Alkazhi is dead. He died a worthy death in the service of his lord and he will be avenged. But not now. Retribution will come, we only have to wait. No one that insults me, kills my messenger, and even kills my commander will get away with it."
The high-rank demons nodded. His words were law so they agreed. There was only one person who could question Salazar.
"Why don't you send me, father?" A normal-looking demon asked.
He looked mostly humanoid and handsome too. If not for the horns, the sharp ear, the obsidian skin, and the red eyes, he would look like a handsome member of another race. He had the charisma and beauty of a demon of lust.
Salazar shook his head. "There's no need for that for now, Bael. Sending you is overkill and too risky. My enemies might try to ambush you if you leave my presence. It is much safer for this demon to come to us, then he will be killed easily."
Bael, the first commander nodded and went back to meditating. "If you say so, father."
"We will wait for him to become a demon noble. Then I'll have my revenge." Salazar said calmly.
Salazar had heard enough about Aeternus to form an idea that he couldn't be killed easily. So he would wait for the time when he can fully wield the full power of his house against Aeternus. There are a lot of reasons to kill Aeternus. That weapon of his alone is more than enough for Salazar to wage war on Aeternus but it is most likely going to fail. He would rather wait for the opportunity to bring his full power to bear so that he can surely nab the Ominous Reaper.
The reason why Bael could question Salazar isn't because of the bond of family. If it were so, Bael's numerous siblings won't have been pushed to their death by Salazar. It is because Bael is special and strong.
It is because Bael is strong is why he is even alive. He is useful to his father, so he lived. He is also too useful to be sent to kill Aeternus. He is sure to kill Aeternus but Salazar doesn't want to risk it. When you gamble and lose, you feel the compulsion to continue gambling to recoup your loss. Salazar has lost Alkazhi, he is weakened by that loss and is feeling compelled to recoup his loss. But he isn't going to risk one of his trump cards for becoming the next demon lord without full certainty of success.
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