"What is going on here?"
That day, Lucifer had only gone out shortly to get something that he left in another universe. As a cosmic being, Inter-universal teleportation was a walk in the park for him, so he opted to make a quick trip back to the last universe the duo was in.
Due to his increasing amount of enemies, Lucifer conquered other universes and used them as decoy 'Hell' universes, to fool his enemies and keep them from getting to the real one.
He left Alexia in one of these decoy universes, only to come back and discover an unconscious Alexia surrounded by over a dozen inferior-stage monarch realm existences.
He identified them as the brothers of Alexia's father, ones who reduced themselves to 'dogs' who did the bidding of her grandfather, just to get the old Supreme Ruler's favour.
Seeing them almost kill Alexia, someone he took as a disciple, enraged Lucifer to no limits.
[Authority of Destruction]