“Adam will say what he wants, but I was the initial conqueror! I could charm anyone. Even Alastor will fall for me!"
-Lucifer, 5 minutes before the disaster. Probably
Or: Lucifer tries to repeat his hellish conqueror tactic, which has only worked once, with Lilith, before people had standards.
Step 1: Save him from the disgusting asshole that is the first man.
Step 2: Show him the wonders of free will.
Step 3: Make him laugh (ducks?)
Step 4: ... Take him out to dinner?
Step 5: Infernal-style wedding!