For Love of Evil by Piers Anthony

Thus the worthy crusade became unworthy almost as it formed, and Parry's grief was only a tiny part of the result.
     
    Another strange thing happened in this period. The drop of blood on Parry's wrist continued to heat, seeming to possess a kind of life of its own. Finally Parry realized that it might be Jolie's spirit trying to communicate with him. "Jolie," he said. "Come to me!" That was all it took. Her ghost rose from the blood and hovered before him, vague and wavering, but definitely present. Thanatos had spoken truly; she was with him, in the blood!
     
    The ghost could not speak or act. But as time passed, he encouraged it, speaking to it, loving it as the remnant of his wife. Gradually it learned to manage, until it was able to assume her living form. Bit by bit, she learned to talk, not verbally but by sending her thoughts to his mind as if in speech. Progress was slow, so that later he could not remember when the stages of her renewed presence occurred. But he had his wife again!
     
    But his grief for her remained. This was the mere shade of Jolie, and could never match the living presence of yore. Still, it was a great improvement, and it enabled him to deal with his grief more effectively, and to focus instead on what he intended to do about his vengeance. He still did not dare to practice magic himself, but he continued to rehearse the spells in his mind, perfecting them for the time when he could safely practice sorcery again.
     
    That year a former Italian soldier, who had renounced his ways and become devout, set out to preach. He was Giovanni di Bemardone, and when he took his small band of followers to Rome, he was permitted to form a band of friars. Now his mission was spreading to other countries, and a group came to France. The originator called his mother the Lady Poverty, and his father the Lord Sun, and his values seemed much like those of the Brotherhood Parry associated with. They called themselves the Franciscans, because of Giovanni's father's travels in France.
     
    The local friars considered, and decided to join the Franciscans. In this manner they achieved the approval of the Church. They continued their singing and preaching much as before, but now their influence was greater because of that approval.
     
    In 1213 Simon de Montfort, the leader of the crusade, won a victory at Muret that made the fate of the Albigenses certain. Parry felt private anguish, but said nothing. As long as the crusade continued, he had to remain in hiding.
     
    In 1214 King Philip of Prance won the battle of Bouvines, and established the French monarchy as dominant in Europe. Parry continued singing, preaching and thinking. In 1216 Dominic Guzman, of Castile, who had been preaching to the Albigensians, was given a house for his growing band. Parry attended, providing moral support as a representative of the Franciscans. The Dominicans, officially the Order of Preachers, became known as the Black Friars, because of their black mantle over the white habit. They were more interested in the philosophical aspects of evil than were the Franciscans, who simply preached the virtues of poverty and humility. In 1221 Dominic died. The Franciscans held an assembly, becoming more formally organized. Parry, as a member in excellent standing, could have stepped into higher office. But his thinking about Lucifer caused him to do something others might have deemed foolish: he decided to leave the Franciscans and join the Dominicans, because they seemed to be orienting more specifically on the problem of evil.
     
    Parry had never forgotten the injury Lucifer had done him. Now he was ready to begin moving more directly against the Lord of Evil. Lucifer had to be made to pay. But first it was necessary to study the ways of evil, to ascertain exactly how Lucifer operated. Once the enemy was truly known, he would be vulnerable. Parry intended to be there for the counterstrike against the Kingdom of Evil.
     
    Parry had survived more