One possible title could be 'Lucifer's Abduction of Angels: A Fanfiction'.
A more dramatic title could be 'Lucifer's Sinister Plot: Kidnapping the Angels - Fanfiction'. It gives a sense of Lucifer having an evil plan, which adds more intrigue to the story.
Maybe Lucifer kidnaps the angels because he believes they hold a secret that can help him regain his former glory. He subjects them to various forms of interrogation and tests in his lair. The angels, on the other hand, are trying to keep the secret safe while also looking for a way to escape. Meanwhile, the other celestial beings are searching for the kidnapped angels and preparing for a possible battle with Lucifer if he doesn't release them.
One possible title could be 'The Kidnapping of Harry by Lucius: A Fanfiction'.
One possible title could be 'The Encounter of Lucifer and Sabrina'. It's simple and straightforward, giving a clear idea that the story is about the two characters coming together.
How about 'Lucifer Morningstar and His Encounter with the Male OC: A Fanfiction'? This title gives a basic idea of what the fanfiction might be about, that is, an encounter between Lucifer and the male original character.
Sometimes other characters from the 'Lucifer' series can also play important roles. For instance, Amenadiel might get involved. He could be trying to stop Lucifer from doing something he believes is wrong, or he might have his own reasons for getting in the middle of the situation. Maze could also be there, either helping Lucifer or Chloe depending on the story's direction.
In some fanfictions, Lucifer could kidnap Chloe as part of a plan to prove a point. For example, he might be trying to show her how vulnerable she is without his protection. This could lead to a series of events where Chloe discovers new aspects of Lucifer's world and her own place in it.
One possible scenario in this fanfiction could be that Loki disguises himself and lures Spiderman into a trap. He then transports him to a different realm where Spiderman is completely out of his element. Spiderman would have to rely on his wits and basic powers to try and escape Loki's clutches.
One idea could be that Madara kidnaps Naruto to use him as a bargaining chip against the Hidden Leaf Village. He might want to force the village to give up certain secrets or strategic locations. Maybe he believes Naruto's unique power can be harnessed for his own evil plans.
One idea could be that the Joker kidnaps Batman to force him into a series of cruel 'games'. Maybe he wants Batman to choose between saving his closest allies or innocent civilians, testing his moral limits.
One idea could be that Lucifer from 'Lucifer' enters the world of 'Supernatural'. Maybe he teams up with the Winchester brothers to fight a common enemy, like a new type of demon that is causing chaos in both their realms. He could use his devilish charm and powers in a way that the Winchesters are both skeptical and intrigued by.