Aaran wasn't lying when he told the high priest he could die. The Emperor was no fool. Even if Aaran hadn't informed him about what he had planned, he would know who saved Aurelia.
When that happened, he would have marched down with his army and executed everyone for using or concealing knowledge of dark magic. That's why Aaran sent him the letter, but the Emperor wasn't the only one who received the letter.
The press media did as well. Aaran did it so that the Emperor couldn't hide his confession and punish all of Aurelia. That was also the reason he asked Lucien to hit him.
Aaran's family doted on him, they would never harm him. The mark of that slap would symbolize Aurelia disowning him. The official letter could wait, meanwhile the slap would extinguish any hatred other kingdoms might have for Aurelia.
