Sense of value.
Bologue always believed that humans are social animals, yearning to be needed by others to prove their own existence's value.
When a person has no connections with the world, it's naturally hard for them to find their own value of existence, leading to doubts about their meaning of existence, giving birth to numerous troubles, and mental tortures like depression.
This can be seen from the members of the Undying Club, these isolated Undeads hold no meaning or value to the world. To pass the long years, even the former Night Race Lord twisted into a famous pole dancer.
Whenever thinking of this, Bologue feels the world has gone mad.
"Hmm, I know of similar theories, evaluating whether a person is a participant in the world or merely an observer," Bologue followed Olivia's words, "You've always been an observer, hiding in the night, watching the tides of time, living in this world yet feeling no real sense of being alive, like an inconsequential phantom."
