Part of the 100 Themes Challenge I am (slowly) working on. Also posted on AO3.
In his spare time, in between battles and strategy and diplomacy, Robin reads. He loves reading the stories and legends of old, finding the connections between the hero king of old and Chrom. A smile spreads across his pale lips as he flips through page after page of tomes in House Ylisse's library, finding beauty in the history of this foreign land and its reflection in the strength and bravery of its heir.
He loves him.
They love each other – perhaps too much, constantly in each other's presence, meeting alone and behind closed doors often enough that even Chrom, the densest person in the army, catches wind of the gossip.
"We're only close friends."
But it's never just a strategy meeting.
And it's never just sex, either.
It's sudden, panicked, and Chrom tells him one day that he's getting married. His face is flushed with crimson shame beneath messy blue hair as he explains that it's not right, nor fair to Sumia, for her husband to have eyes only for his tactician. Robin, however, sees through him, as he always does. Nothing Chrom does can change their bond, the deep unity of body and mind they share, the one thing they have that no one else does. So still they love, they love, they love, they love.
They love, and it hurts.
Chrom tries to be a good husband, and when Lucina and Cynthia come around, a good father. He's much better at the latter. After all, it isn't difficult to fake a satisfying marriage to a pair of toddlers.
It's considerably harder to fake it to Robin. Nearly impossible, in fact.
Robin watches Sumia. He sees a certain connection in her particular grace, her fortitude when she wields her lance and flies, putting every effort into supporting her commander. She's Caeda, the princess. He's Marth, her lover, the prince. And Robin is no one – Robin does not have a place in their story. He may be intelligent and seductive, but Sumia has charmed Chrom with her kindness, her sweetness, and that's something Robin can't do for him, especially under the critical eyes of the court. He loves Chrom, yes, but sees the higher powers at work that keep them apart – they simply aren't destined to be, not when Chrom has a wife and children and an entire nation to care for. The last thing he needs is a secret lover complicating things.
This is impossible. The general and his chief tactician? It just... it wouldn't be right.
Perhaps this is why, when Robin returns to read his favorite history books again, a grimace darkens his face. Perhaps this is why he abandons the library altogether, spending as much time away from Chrom and the palace as possible, until the war effort pulls them together again.
Perhaps this is why Robin's last memories are of the corpse of the man he loved, bleeding out from the sickening wound that he inflicted.
It feels like being a mind without a body – only feeling, only regretting - when he lets go, allowing, willing the darkness to consume him, erasing from history the man who failed the only person who ever completed him.