#1 Introduce a weakness to the character

The Fiend has been a monster so far. His opponents are yet to find a way to keep him down for a three-count. The Fiend has soaked up everything his opponents threw at him. Finishers, weapons, you name it. However, how long can The Fiend incapacitate his opponents without letting anything affect him?
Introducing a weakness can bring a lot of excitement to the character. People online have come up with theories that The Fiend draws power from the red light that surrounds the arena during his matches. Even Bray Wyatt himself dropped a hint after winning the Universal title on Twitter. He said,
Is this man the funniest man in wrestling?
It should be interesting to see when someone finally founds a loophole in The Fiend's strengths and we could finally see the monster vulnerable for the first time.