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Tear Jerker: Progress
Princess Luna's account of the young warrior she met long ago in "Luna vs. Storytelling". He did everything he could to woo her, but ultimately had to commit a Heroic Sacrifice to slow down the Smooze. Now she can't even remember his name.
Luna's paramour is mentioned again in "Luna vs. the Dreamlands", when she does some "spring cleaning" in the realm of dreams, and reminisces on what might have been when she finds a monument to him in a dream-scape she made.