I've read 'Lucifer's Heart'. It's a fanfic that focuses on Lucifer's journey to understand love. He meets a character who challenges his beliefs and slowly he starts to change. The way the author writes about Lucifer's transformation due to love is really captivating. It also has some really good dialogue that adds to the overall charm of the story.
One great 'Supernatural Lucifer Love Fanfiction' is 'Lucifer's Redemption'. It shows a different side of Lucifer, where he falls in love with a human. The story is really engaging as it delves into the complex emotions of both the characters. It also has some great action scenes that are typical of the 'Supernatural' world.
There's this fanfic called 'Love in the Cage'. In it, Lucifer is locked away but still manages to find love. It's interesting because it plays on the idea of love being able to break through even the toughest of situations. The author does a good job of describing Lucifer's internal struggle between his dark nature and his new - found love.