Lucien was lying unconscious in Aiden's arms. And he protectively wrapped his arms around him, not daring to let him go a second time.
The bloody parasitic veins tightened around the demon's intangible form. Aiden can see the demon's face, but he is a casper like existence. Aiden had been vigilant of him from the start. He could tell that poor guy his sister fancies was enslaved by this disgusting 'thing'.
That guy willingly became a slave in order to survive. Because he wanted to see Alicia again. And now that she's here, it was equivalent to having his wish fulfilled and he should be devoured completely by this demon.
But this disgusting trash was not satisfied. He wanted more. He wanted to get a perfect vessel that could accommodate his power to the fullest.
And Aiden was his perfect candidate.
Just as the demon noticed and wanted Aiden's body to be his vessel, Aiden also noticed his power and identified him as an Ancient Demon.