As I know it, Undertaker's real name being "Adrian Crevan" is just something fans made up and a persistent rumour. I am not in the fandom for a very long time now, but I know that the name came from a headcanon which was once submitted to kuroshitsujiheadcanons.tumblr.com. I searched for a while, and actually found the headcanon! [1] I hope that helped!
thank you!
TerriaNight what about Grell Sutcliff? Does he have such a name?
i mean it's : Undertaker - Adrian Crevan
Grell Sutcliff - ???
TerriaNight what about Grell Sutcliff? Does he have such a name?
i mean it's : Undertaker - Adrian Crevan
Grell Sutcliff - ???
Pretty sure Grell Sutcliff is just Grell Sutcliff. Momo literally clarified that Adrian Crevan's a made-up name by the fans.
TerriaNight what about Grell Sutcliff? Does he have such a name?
i mean it's : Undertaker - Adrian Crevan
Grell Sutcliff - ???
As I know it, Grelle does not have such a made-up "real" name like Undertaker has. Of course, I could be mistaken because I haven't been in the fandom for that long. However, even though Grelle could have one somewhere in some lonely little fanfic or on a blog etc., I guess this name is not as prominent as "Adrian Crevan." (Really. This name sounds actually rather stupid to me. Or is there some joke behind it which I don't get?)
Undertaker only has such a made-up "real" name, I guess, because Undertaker is definitely NOT his real name. "Grelle Sutcliff", however, whether it's his/her/their real name or not, just works fine. Like nobody goes and gives Ciel a new name. (Except in case of the TCT or of some kind of genderbend thing.)