In life, Boris Valerious tried to defeat Dracula by finding out where his castle was. He would stand in front of the Valerious Castle's map painting for hours looking for Dracula's lair, tearing though the family archives in the tower, spending year after year looking for answers. In 1887, just after the incident at Castle Frankenstein, Boris went missing in action. In 1888, Dracula revealed to Velkan that he had captured Boris a year ago and tried to use him in an experiment to bring his unborn children to life, costing Boris his own life. The experiment failed because Dracula deemed that Boris was useless and tried to do so again with Velkan.
When Dracula was finally vanquished by Gabriel Van Helsing, Boris Valerious was finally able to rest in peace and enter heaven with the rest of his family.