With Black Butler being one of the first anime I watched my initial thoughts on it was that it was strange. over time it became one of my favorites. There were many characters I loved and hated. But this last season was by far my favorite.
While all three seasons have a bit of darkness in them this last one felt like it had a much darker feeling to it. It tells the story of Ciel and Sebastian investigating the disappearances of children and going undercover in a circus that is suspected to be involved.
Its always been known that the servants of phantomhive manor were not normal. though it has been a while since I have seen the first two seasons I do remember hearing that they were special. You get a deeper look into just what these servants are in this season, and this made me happy. They were not just these goofy people who couldn't work properly.
We get a deeper look into Ciel's dark past and find out the circumstances behind how he met Sebastian. It was interesting to see this because it kinda changes you point of view of Ciel, and makes you look at him in a different light.