“ The members of the party has unknowingly been infected by a mysterious plague and have been spreading the virus for quite some time now while adventuring. They start to hear rumors of all the cities in quarantine after they travelled trough. Will they discover the source of this? Will people start to avoid them, try to kill them?”
“ Diseased people, (leprosy or any other such fear inducing disease) when traveling, will often times wear a cloak that entirely covers their body and ring a bell as they travel, used as a warning for any others to stay away. Could be used for a disguise or safe passage. ... you meet strangely cloaked people, sometimes ringing a bell. 'Please give us something to eat, mighty heroes!' This is time to show how good they are.”
“ The two cathedrals in the Citadel stubbornly ring their bells two minutes apart, since each believes the other to be too early or too late respectively. This has been done for over two hundred years.”