I see Dralmorrer disillusioned from the Cult of the Dragon, but not any less fervent as a member of the Eldreth Valuuthra. He will continue his Elf supremacist actions and will be a general antagonist in any campaign that will use one. Just have his presence introduced in any means plausible. Maybe a wanted poster, or a roadside ambush, or have them witness an assassination, or even have them walk into a slaughter of an Half-Elf family with the mark of the Eldreth Valuuthra for example. Have Dralmorror Borngray pop in and out during the campaign annoying the party whenever the campaign needs to slow down somewhere.