Why he has the purple, pink & black stuff on him
After the End Crystal exploded, pieces of it went into him.
The purple and pink is because of the End Crystal, pieces of it went into his eyes through his blindfold (the blindfold somehow healed itself,) and made purple come from his eyes and stain his face when the liquid purple stopped coming.
The black is from prolonged exposure to the void, along with the black also being healed wounds that were caused by the End Crystal.