Hi there. From the sounds of it, it's likely someone obtained one or more of the usernames and passwords you use to sign into Xbox, PS, and/or Steam and sold them. If you haven't done so already, we highly recommend you change your passwords and enable 2-factor authentication or passkeys. Bungie profiles are created by signing into B.net with a platform account login. A profile doesn't have a separate login of its own and is just used to view and manage some things for the character sets of those accounts. Your profile can be signed into using any of the linked accounts, which is how they added the Epic account. Note that as of March 25th, once an account is linked to a profile it's permanently linked. Bungie will not forcefully unlink or remove an account under any circumstance. At this point, you're facing a tug of war until one of you gives up, so your best option is to talk to Epic Support and maybe they will ban that person's account. For more info, see the [url=https://help.bungie.net/hc/en-us/articles/360049498031-Destiny-2-Cross-Save-Guide]Cross Save Guide[/url].