A choice?
From the very beginning, Reinhardt had pursued only the path of the Knight.
The Ancient Black Box possessed immense power, but it was already tainted by the Void Realm. It would be an exhaustive effort to forge it into a Knight's Treasure just to grasp a greater Extraordinary Power.
He might as well dive headfirst into the Dark Abyss and pledge allegiance to Avernus.
At the very least, he would gain the Mighty Power of the Supreme Great Demon Level.
Interestingly, the moment this thought crossed Reinhardt's mind, he clearly felt something watching him. The Divine Emperor's Fury, slung across his back, spontaneously ignited with the Divine Emperor's Flame.
Then, Reinhardt laughed.
The low chuckle sounded especially muffled as it came from his Full Coverage Helmet.
It was so strange that the other members of the Vengeance Angel Squad traveling with him thought Reinhardt might have suddenly gone mad.
