Damian and Jon, past and present.
(a poem)
Red lines only: Damian, age 12, is laying back on the grass in the Kents' farm, cloud-watching with Jon. He thinks about how Jon is too innocent, but maybe that's because he is too bulletproof for the world to pierce him, taint him. And Damian, twisting his own knife in his own heart further, knows he's crueler than his friend because he has made horrible mistakes.
Blue lines only: Jon, aged 21, (in a Dark!Jon au) is reminscing about the days when they were younger. Damian survived in this world with his heart intact, but Jon has grown into a man with destruction at his fingertips and hate in his heart. And Jon thinks, Damian was able to let his mistakes smoothen his edges, instead of sharpening them—like what happened to Jon.
When both red and blue are read together, it's from Jon's pov, expanding on his view. He thinks about how they were too innocent for the world, but somehow Damian's heart was bulletproof.