Joan-Carles has never met someone who didn't deserve to go to Hell. All the more just that he lived in Cheliax, where everyone's proper place was to go to Hell.
His mother had not loved him, a betrayal whose sting never lessened with time. He was abandoned at the orphanage was at the age where he could just barely remember his mother's face, but little else about her. Of his father nothing was known for certain, and his mother's guesses never made it to his ears. The carers at the orphanage put in just enough work to not get punished by their superiors, and never received a punishment without passing it along to one of the children in their care. The other children mocked him mercilessly, and ensured every misery was shared in full by all their fellows.
What can men do, against such reckless hate? What more hope does a child have? His only solace was their weekly lessons at the chapel, where the other children were silent and still out of fear of punishment. He drank deeply of the sermons, learned well the lessons, and bent his heart on Hell, and the torments that all his tormentors would themselves befall in turn. He noted well that the boys at the orphanage measured strength by height and muscle, the girls by sharpness of tongue, and the cleric had them all overpowered, adults and children both, with his pentagram and robe rather than any personal powers. Joan-Carles was a slight and short boy, underfed and underexercised, and so he bent his whole soul towards a pentagram and robe of his own. The other students hoped to prove themselves prodigies at math, on the wizard track, or to simply escape the wrath of their teachers; he focused instead on devotion to their fearsome Lord Below.
They saw something in his eyes; that he meant it. They still extracted their price; he was worked ragged with extra chores to earn a private consultation with the cleric, and then his recommendation came at no small pain and a rather foul taste. But Joan-Carles made it to seminary.
The other students at seminary could hardly be called his fellows. They were craven supplicants, prostrating themselves before the majesty of Asmodeus, desperate for a scrap of his power to use for their own petty ends. Many of them harbored doubts, easy for Joan-Carles to see and raise in their theological debates, hammering at their weaknesses. Only a handful of them grasped the fundamental justice of their situation, that 'as above, so below', that the miseries they caused on the surface would be repaid a thousandfold one they had passed thru the River of Souls. Joan-Carles was barely taller than a halfling, ugly to look at with his misshapen features and scars from beatings; he had no hopes for personal power or professional advancement. Joan-Carles had only one prayer; 'O lord, may we all get what we deserve, good and hard.'
When their classes were complete and they went into the chambers to pray, he was Chosen immediately. While he had impressed Asmodeus with how much of himself he had burned away in pursuit of vengeance against the world, the Church nevertheless needed quality for its roles of importance. He was appointed a deacon in Ostenso, and he obeyed without question or complaint. He had a pentagram and a robe, now; he had always been hated by everyone he saw, but now he also had their fear, and he could repay them for their hate with pain.
One day, he was in the street, an urchin running away. He didn't see what the child had stolen or who was chasing him; he just saw in the boy's face that he wanted to be somewhere else, quickly, and the look of guilt that couldn't be hidden from Joan-Carles. There was a flash of one of his childhood tormentors, and he issued a command, hardening his squeaky voice as much as he could. "Stop."
Joan-Carles imagined a moment of hesitation, and then the urchin kept running, falling dead after another step. As he deserved; Asmodeus would finish his punishment.
Asmodeus grants the Legislation sub-domain, and children don't have many hit points.
As a standard action, you can command a creature within 30 feet to refrain from committing a particular action (including any referenced in the spell forbid action). If the creature performs the named action before the beginning of your next turn, it takes 1d6 points of damage + 1 point for every 2 cleric levels you possess and the effect ends. This is a language-dependent effect. You can use this ability a number of times per day equal to 3 + your Wisdom modifier.