One sympathises with Wills; he falls out with his grandmother (4-6)
I believe the answer is:
well-wisher
This could be a double definition.
'one sympathises' is the first definition.
(a well-wisher sympathises with people)
'wills he falls out with his grandmother' is the second definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'with' is the link.
(Other definitions for well-wisher that I've seen before include "One desiring another's happiness" , "Person sympathetic to a cause" , "Someone hoping for another's happiness" , "Person concerned for another's welfare" .)