Not good at writing this kind of stuff...
They are probably a pair of unlucky cousins. The cousin is very weak and sensitive, and sometimes he is induced. The cousin seems to be ordinary... But in fact... He can transform at certain times? Can you be a ghost?
Actually, I don't know how the story will develop, so let's leave it like this...
An unlucky little cousin with a terrible past experience (what a long attributive) comes to his cousin's house. What will happen next...