"I solemnly swear I am up to no good!" "I solemnly swear I won't date one of your brothers." One promise to her best friend was never so hard to keep. When eleven-year-old (Y/n) (L/n) made the promise to her best friend Ronald Weasley she assumed the schoolgirl crush would fade but three years later, she still can't shake her feelings for the twin who drinks cinnamon tea. When a secret relationship manifests, how will she manage to tell her best friend?