Archenemy and Adventurer is a Log Horizon-Maoyu crossover fic by DQueenie13, which takes place after the end of Maoyu and during the current timeline of Log Horizon.
Summary[]
After ascending the Pillar of Light and ending the cycle of wars between the Human and Demon realms, Hero, Demon Queen, and Female Knight are taken to another world as a reward for their efforts. This new world is the world of Theldesia, the setting of the popular MMO Elder Tale, where an event known as the Catastrophe trapped the game's players within that very world. What will happen when Demon Queen and Shiroe meet?