End of the Monster Horde Invasion
There are only two people who know that he got the Treasure Chest Fruits.
One is the Ninth Prince who has ascended to the Second Floor and thinks that he is a Monster King.
As for the other one, he is Guardian Dan.
After Aeon used his [Fire Naga], he knew Guardian Dan would recognize him right away.
Thus, he intentionally chose to stay close to Guardian Dan, waiting for a perfect opportunity to assassinate him.
Although he could openly kill and not worry about his safety on the First Floor, it would become complicated on the Second Floor as the members of the Elite Families stationed there would be more powerful and have more trump cards to capture him.
So, when the Four-eyed Bat King attacked, Aeon felt it was the right opportunity for the assassination.
'Furry, be quick.'
Of course, for the assassination, Aeon was not going to take the action personally but quietly sent the Spider Queen.