Their deaths- triggered by Sinclair's fear-inducing henchman Scarecrone causing them to remember the mugging, driving them to flee Chill by running off their balcony- prompt Bruce to become Batman to investigate, Gordon having written their deaths off as an accident and Bruce unwilling to investigate himself because of the risk to his new wife, Julie Madison. In the Flashpoint event, an alternate timeline is created where among other massive changes, Thomas Wayne rather than Bruce appears as Batman. Details after the events of his son's death remains ambiguous, but Thomas is shown to have Joe Chill's gun in the Batcave's trophy display, suggesting Thomas got his revenge.
Thomas Wayne
Bruce