Killed by Strahd von Zarovich after being driven out of Vallaki.
A famed vampire hunter but is getting old now.
Found a way into Barovia to defeat Strahd von Zarovich and/or go out in a blaze of glory.
Ezmeralda was his protégé but they had clash of personalities.
When young Ezmeralda's family kidnapped his son and caused him to be taken by a vampire. Rudolph hunted them down and questioned them but spared them and went to try and save his son - but he was too late.
Ezmeralda was disgusted with her family and ended up allying with Rudolph.