Shingeki no Kyojin: Before the Fall

A baby is found crying in a mass of Titan vomit, amidst the dead titan flames. The child is called "child of titan" and is essentially hated by the people inside the walls. He also seems to grow unnaturally fast. Named Kuklo, he parts himself from his past/upbringing and gambles on the fate of humanity by enlisting in the scouting legion.