That wouldn't make sense because vincent was in the same room as the undertaker in the circus arc. Unless there was some awkward stunt double, highly doubt it. Its a good start to a theory though.
Personally, I believe that undertaker was in love or married to Claudia Phantomhove, Ciel's grandmother. Therefore making him an earl.
well, isn't someone became shinigami because the do suicide?
Maybe it's true if undertaker is claudia phantomhive husband and vincent's father...
i think undertaker shows up after the death right?
It never was revealed if he did or not. Only that Madame Red arrivedvat the burning manor. QAQ I miss her...
Timeline does not fit - see my comment further up.
Theory: Undertaker is Vincent Phantomhive's father.
It's a cliffhanger but at least we know how Shinigami's are made.