You should read up on the wreck of the whaleship
Essex. Fascinating adventure; testimony to human endurance under extremely adverse conditions. It was the event that inspired Melville to write "Moby Dick".
The survivors were found adrift in rotting boats, gnawing on the bones of their shipmates, starved and delirious. Even after their rescue and return to a "normal" lifestyle, they carried some peculiar quirks for the rest of their life, such as the sailor who lived many years with an attic full of canned foods.
As for the German story, I found this to be curious:
Mr Meiwes, a computer expert, met 43-year-old Bernd-Jurgen Brandes in early 2001, after Mr Meiwes advertised on websites for "young, well-built men aged 18 to 30 to slaughter".
Obviously, they were both mentally unstable.