Blue Revenge Arc - Tumblr Posts

I don't know why I get the feeling that undertaker is one of the Phantomhive's descendent.

Like, there is some relationship between Claudia Phantomhive, Ciel's (and his unnamed twin brother who plays the protagonist all along) grandmother, and undertaker which is like marriage or like undertaker is a member of Phantomhive family or something?

Because he protected Ciel from burning and is like ruining the whole world's dead people and killing living people just to find a way to make the real Ciel live.

Another reason is because it was once said that Shinigami-s were also humans, but they committed a suicide and as a punishment had to collect others souls and witness death until the punishment was over.

Also, in one of the side stories, he cries while seeing Vincent Phantomhive's photo, Ciel and the protagonist's father.

And, please clear this doubt of mine

Is the Blue Revenge Arc, the final arc of black butler?

Because the series is going on since 2006, and it is already like 18 years.