Paul was one of Father Joseph's wards who took so well to the lessons he had to teach that he Embraced him. It pleased him to capture the boy forever in his youthful state and Paul's mind, twisted and damaged by years of systematic abuse at the hands of the Tzimisce, was in no condition to argue. On the contrary, he has adapted well to his new state, mostly due to the means of his rationalization of it.
When he was still living on the street, Paul was one of the young adherents to a belief based roughly on Christianity and child-invented fantasy that placed the world in the middle of a battle between God and his angels and the Devil and the demons of hell. With his abduction and introduction to unimagined abuses, he has merely come to belief that his past sins allowed the demons to come get him and induct him to their cause.
His religious beliefs have been rapidly stripping away his humanity ever since. Assisting his sire in the torture and rape of other young boys, he's allowed himself to adapt completely to his new role as a demon and has become just as vicious and sadistic himself. Moreso, in some respects, as he lacks the odd form of guilt which still lingers in Joseph's mind. He also as the benefit of a gift for Dementation, something his sire doesn't share, which allows him to amplify the fear and humiliation of his victims, whom he carefully inducts into his view of things while they suffer.
The boy's state and progress to Cathari have been observed by Malena who is rather pleased. She sees the boy as a potential saint of the faith in his own right and hopes to raise him up to the same level as her own sire. Meanwhile, Paul persues and tortures street children and vagrants, subjecting them to his disciplines and his madness. Thus far, he's not been caught, but the police are beginning to notice the leavings of his efforts and the Sabbat Inquisition is sure to put a stop to him as soon as they realize the extent of his madness.
Paul is a very disturbed man (he's lived too long to really be considered a boy anymore). The abuse he has suffered, coupled with his religious delusions, have made him a sociopath and he's become increasingly unable to control his sadistic impulses as he's 'progressed' along this path. This leads to him being very obviously insane to any who meet him. The depth of his cruelty are reflected in his eyes and he isn't able to pretend to be normal for long. Usually only long enough to snare a new victim.
Paul is very close to his sire, the sort of fanatical love and loyalty that only insanity can breed. He is also fond of his "Uncle" Beranger, the man who first delivered the boy to Joseph and who sees him as a fine example of the righteousness of his activities. He has adopted the rest of the Prejeans as his family, too, but finds Sevis to be dull and uninteresting (an attitude which annoys the vain revenant to no end).
He likes Ange, but only because she is fun to torture and watch squirm, and hates her childe. He has plans to kill Louis, should the opportunity present itself (or the right mood strike him). He thinks very little of the other kindred in the city, who he finds boring in comparison to his own brood. The only exception to this are the Cathari Setites, who he respects merely for the reverence they show Malena, whom he views with complete awe and would likely equate to Satan himself were she male.