I love
Catherine but hate
Cathy.
I love
Gregory but hate
Greg.
I love
Patricia but hate
Patti or
Pat.
I love
Thomas but hate
Tom and
Tommy.
I love
Violet but hate
Vi.
I love
William but hate
Bill,
Billy and
Will.
I would probably use all these names as MN. I would consider
Violet as a FN because I'm not convinced that everyone would shorten it to
Vi.