Karl gets a migraine and a nose bleed after going back and forth from time periods.

He has a major fear of forgetting everyone that he cares about because it's now becoming more common for him to forget their names and who they are.

Karl's attire will soon become all white and grey, and his memories will be forgotten and cant be given back.

The price of going back in time is loosing all your important memories and forgetting who you are as a person.