So old cat is totally scared of new cat. We have done all the introduction things properly, kept them in separate rooms, introduced smells, made new cat smell of home etc etc. New cat is a rescue cat, 3ish year old tom cat. Old cat is about 4years old and female. New cat is completely not fussed and not aggressive towards old cat but old cat just flees outside and refuses to come back in the house.
What can I do to help old cat stop being such a scardy cat?