What kind of man Rainsford thought he was (zaroff) , and to the readers ??

Do you mean the type of man Rainsford (the character) thought he represented to Zaroff and the readers? Or, did you mean the type of man the author wanted to represent Rainsford as to the readers and Zaroff?

I mean what kind of character is zaroff towards Rainsford , and readers ?

Oh, Zaroff is your standard antagonist with a slight twist. Besides being a crazy eccentric murderer, he is refined. He is a generous host who is polite and well groomed. He has a lot of wealth and has expensive tastes. Both Rainsford and the reader find he is mentally unstable. The guy basically lives alone, except for Ivan, and hunts people all night for fun.

No. For the first time in that whole grade duration , I see someone who is saying on our flat and lofty antagonist "aguy" , Wow , currently the most specified description from the text is "He is an aristocratic man" and also "disarming" he is having like awell-accomplished manner on how to deal with his huntee . He is also supported by Ivan and he's nothing without him as he said "But, Ivan can repair it " admitted Zaroff .