8. The Inconsistent Logic Of The Cure
The show initially claimed that if a vampire takes the potion then they will lose their immortality. However, if any other vampire wanted a human life they would have to drain the person who drank the cure of all of their blood.
The 1994 version of the cure was discovered by Bonnie when she was searching for Silas' Tombstone in Nova Scotia's prison world and she took it back to Earth. And when Elena has the 1994 cure coursing through her veins, Bonnie takes some of it and injects Stefan which turns him back into a human and there was no draining involved. So have the rules of the cure changed? If so, why is it never explained?