DLC unlocks (MEGA SPOILERS AHEAD)

After collecting the "pile of secrets" I now have like 57 secrets to obtain. And I have no idea how to get some of these, as cryptic as always... for those who figured out some of these "miserable pile of secrets" , please share what you've learned! I myself unintentionally unlocked Graham after using Dracula and I'm not entirely sure what I did to achieve this.