Here are a few stories I've found and thought were really good:
Story: Speaking in Tongues - Those surrounding him are suprised when Lucifer speaks multiple languages
https://www.fanfiction.net/s/12935954
Story: This Isnt What It Looks Like - Lucifer on his balcony debating whether to use his wings
https://www.fanfiction.net/s/12946477
Story: Darkness - an accident at a crime scene leaves Lucifer blind. How does the former angel of light cope with the dark.
https://www.fanfiction.net/s/12988543
Story: Freedom (warning for swearing. But only a couple of times and it makes sense in context). A take on Lucifer's internal thoughts as Maze cuts off his wings.
https://www.fanfiction.net/s/13213667