Divine Intervention
Tales of angels from up high messing with Tokyo in their own ways.
Initially a Xana and Gabriel shipping fan fiction on AO3 inspired by very well done, commissioned fan art. It gradually became a recurring series and a means for Raindare and Interipelli to workshop ideas off each other.
Its climax is a showdown with the true final boss of D2 Megaten circa 2023.
Though there was an uninspired sequel series drafted by Interipelli, it lost its footing as adapting D2 Megaten's world of eternal 2017 to the world of 2024 proved difficult and unappealing to Raindare.
There have been rumblings of a brief, "true" revival if a buffed to the gills Malice variant of the 2023 true final boss was ever released, though who can say.
In several respects except for continuity, Shin Devil Children is the true successor to this set of Megaten fiction.