Complex sentence: However, Cocytus developed a respect for the Lizardmen and requisted Ainz to show them mercy, causing Ainz to place them under Cocytus' supervision and even resurrect those who had perished.
Split into simpler sentences: However, Cocytus had developed a respect for the Lizardmen and requisted Ainz to show them mercy. In responce, Ainz placed the Lizardmen under Cocytus' supervision, even resurrecting those who had perished.