If memory holds our emotional reservoir, both personal and public, what happens if it is erased? There are many real situations that cause partial or permanent amnesia: trauma—emotional or physical, stroke, surgical procedures, and aging. Do we become a different person? Can one lost memory impact all who we are in our character? Why do we struggle so hard to hold on to them even when difficult or painful?
Then as writers we can add in all the fantastical and sci-fi versions too. Think of Farscape with Scorpius chasing astronaut John Crichton across the universe to extract wormhole technology from his mind.
One of the story threads for Season Five of Doctor Who is his realization of a crack in the universe. The Doctor began to recognize that if it reached a person they would no longer exist, as if they’d never been born. He tried to convince a young woman to hold onto the memories. If she could keep hold of them then the missing person would still exist in her heart.
If you knew that a special memory would be erased forever, what would you do to hold onto it? Write a scene where your character discovers what you have done and reacts to it.