Jocinero is found in the Sleeping Canvases inside a painting of a bull, directly to the left from the second Prie Dieu altar. He is a large infant with a golden head and holds a horn that wraps around his wrist. He is presumably the first of the Children of Moonlight.
Jocinero was born from the moon and a bull, and from him came the Children of Moonlight, who are meant to protect souls in penance. His dialogue tells that the Miracle imprisoned them and thus they cannot protect penitent souls. This suggests that Jocinero and the Children of Moonlight are at odds with the will of the Miracle. This is further evidenced by the fact that Jocinero is kept in the Sleeping Canvases, a storage facility for heretical paintings and artifacts.
Item descriptions indicate that a painter created the associated mural as his last work. As soon as he finished, members of the Mother Church took it away and he never saw it again. This description also implies that the Church may have even commissioned this painting.
Upon first meeting Jocinero, he will ask the Penitent One to find the other Children of Moonlight and guide them back to him. At least 20 must be collected before he can be seen in the form pictured above, and he will give the Linen of Golden Thread relic. Saving all 38 of them and speaking to him will cause him to give the prayer Campanillero to the Sons of the Aurora.