just thought of something, might be complete bullshit but who knows. So lucifer tends to refer to people by their title, right? (Detective, doctor, brother, etc) and I think this kinda represents how he values who you choose to be rather than what you're born as, like how obviously he finds purpose in defying God (as many of us do). And on top of that, he calls people by their names once they're close, and often in intimate settings, similar to how he handles himself, only revealing himself to those he's closest to and avoiding topics relating to hell and his family except with Linda and/or Chloe, literally the people he's closest to in the universe. So basically, titles hold a lot of significance to lucifer.