Aeternus chose to ignore them after they ran away. He didn't care if they survived his flames or not. They had placed all the inhabitants in a neat formation for him to kill all at once. That's good enough for him. He looted the fortress and went on his way.
There was no resistance in the next fortress. The high-rank demons had disappeared or maybe there were none in the first place. He waltzed in causing destruction and wrecking havoc. He was like an angel of death and destruction, the representation of gloom and darkness.
The next fortress he reached belonged to the disgusting worm fly. It was the one that created the explosion that destabilise his pillar of flaming darkness. It wasn't a selfless act. The worm had a clone back at its fortress or a life-saving method. Aeternus was sure of it when the soul of the worm tried to escape even before the explosion occurred.
Well, it tried to escape. It turns out that chaos energy is highly potent against the soul. Even when that soul has a spiritual barrier around it. The barrier didn't protect it. It was like tin foil against a knife. So it was burned up. But the soul wasn't complete. That's how he knew that worm definitely survived. The rest of the soul had to be somewhere
The fortress belonging to the worm was disappointing. It was calm and orderly since no one sensed that their army commander died. Technically, their army commander died once but is still alive. So they went about their business. It was a shock to them when Aeternus came knocking for his dues.
There was no resistance of any kind from the soldiers. It's all good too because resistance of any kind would have been useless. But the High-rank demon that is the army commander didn't know that. He valiantly chose to fight Aeternus. The ignorant demon shouted to him.
"Stop right there you insolent demon." He shouted in anger before casting spells.
"Use your head sometimes," Aeternus said before going on to kill the demon.
The demon was faithful in doing his job as a vice commander. He expected the army commander to show up any moment and make things right but the worm seemed to be otherwise engaged. Aeternus searched the castle and did not find the worm or most of the useful things in the stash after killing that loyal and ignorant demon.
The disgusting worm had revived with only a fragment of its soul left within a small worm in a safe place within the castle. It had no recollection of events that happened since he tore out a fragment of its soul to create the clone but a quick sensation of the amount of the members of the alliance still alive revealed to it the full picture of its current situation.
"Something bad has happened. Something very bad. There are only 3 of us alive. I can't stay here" The tiny worm screamed.
It knew for a fact that it had died. He didn't know why, but whoever killed it made a flaw appear in the revival method. That means that person had to be very strong. Then there were the dead alliance mates. The least of the worm's problems right now is the lack of support since it is weakened. Demons would rather kill it and feast on it rather than help. The biggest problem is for the person that killed it to still be after his life.
It sped up its growth by eating a lot of flesh it had stockpiled. Then he stuck his most valuable properties into the pouch it had within his body. He ran away from the fortress without telling anyone. It didn't even tell the blade demoness and the serpentine demon that he could sense were still alive. Anyone could be compromised and a weak recently revived demon is a situation worse than showing a sign of weakness.
The worm is weak and at its lowest point as a high-rank demon. The good news is that it will be able to stay in the domain of mid-rank demons for a while until it grows stronger. Dying and reviving can cause you a lot of loss in terms of sin energy. The concentration of ambient sin energy isn't really a priority right now.
So Aeternus got almost nothing from the disgusting worm's fortress. He had to be content with the weapons and armor. He killed the middle-rank soldiers before moving on. His mood didn't improve when the next fortress didn't provide him with a good haul.
The serpentine demon had packed a lot of his goodies and sent them with the high-rank demons that were its subordinates. He chose to wait after he had secured most of his wealth to see if it was being paranoid. It was not being paranoid. Aeternus did come for him. The serpentine demon ran in fright after spotting that ominous blotch of darkness in the distance.
Aeternus tsked when he finally reached the fortress. "He even dares to spoil my fun."
The serpentine demon didn't just run, he told everyone to jump ship with him. It wasn't being considerate. It just wanted to use the hysteria and mass desertion to cover its own tracks so that Aeternus won't be able to find him if he had a method of tracking. Aeternus didn't have a method of tracking but the Serpentine didn't know that because he never asked. It should have asked or not been so paranoid. Now Aeternus doesn't have a fortress to loot. He doesn't even have any interest in torching the place.
The fortress was mostly empty by then. When your army commander says "Run for your lives. We faced the Ominous Reaper and he has come to seek revenge. Save yourselves." Then scales the fortress and runs.
You don't question if this is a joke or a drill. There's nothing funny about it and there are no drills for proper desertion protocols. So you can't mistake this for a drill. You pick a direction and you run for it.