Harry Potter Golden Age

Prompt: “You may forget but let me tell you this: someone in some future time will think of us” (Sappho) - Character A finds letters revealing a same-sex love affair between people in their past. It makes them view Character B in a whole new light.
Suggested Characters/Pairings: Any slash or femmeslash.
Theme/Tone: Poignant but hopeful, Romantic, Exploring sexuality later in life
Additional Info: None