One idea could be a scenario where the Doom Slayer somehow ends up in the Halo universe. He might team up with the Master Chief to fight a common enemy that combines the demons from Doom and the Covenant or Flood from Halo. For example, a new threat that has the ability to corrupt both the technology in the Halo universe and summon Doom demons.
Maybe in the fanfiction, the Halo rings could be used in a different way. Instead of being a weapon against the Flood, they could be a key to sealing portals that the demons from Doom are using to invade different galaxies. The Master Chief and the Doom Slayer have to figure out how to use the Halo technology to stop this invasion while also dealing with their own personal vendettas against their respective enemies.
Chapter 291, ", The Visitor from Beyond", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. The chapter turns that into something concrete by moving from When will the Dragonhawk Third Legion arrive? to Transporting a million troops isn't easy..
Chapter 175, ", "Central Blossom" Army Corps", is the clearest early answer because it turns Alliance Army's situation into a concrete plot event. The chapter turns that into something concrete by moving from Everyone went their separate ways here, each looking for their own... to And he, with the unit that reclaimed the title of Beast Slaughter....
Chapter 321, ", Spiritual Energy Transmission", is the clearest early answer because it turns Spiritual Energy Transmission's situation into a concrete plot event. Early on, Not having to fight is a good thing.. By the end, Subsequently, she was notified by the newly established Psychic....
Chapter 210, "Sweeping Across the Eastern Provinces", is the clearest early answer because it turns Alliance's situation into a concrete plot event. The chapter gives readers a real answer by opening on For instance, they began to gradually accept the "advisory" influence... and ending on Latterly, Yan Fangxu simply made a summary-style military report....
Chapter 174, ", Loyal Heir Academy", is the clearest early answer because it turns Rage Owl Star's situation into a concrete plot event. It opens with Gu Hang simply picked a few random classes and went in to listen to... and closes on Only his most progressive wife managed to maintain high spirits, and....
Chapter 174, ", Loyal Heir Academy", is the clearest early answer because it turns Loyal Heir Academy's situation into a concrete plot event. The chapter turns that into something concrete by moving from He had once been the political commissar of the 7th Garrison Division... to Leaning on his cane, he hurried over but didn't dare to enter and....
Chapter 303, ", Blackbird Battle Settlement, Ironman Puzzle", is the clearest early answer because the buildup finally cashes out in a real clash. A useful checkpoint is the way the scene starts with Matins's gunshot startled his subordinates awake. and follows through with Maybe it was a plot conceived by a Subspace Evil God, with some....
Chapter 132, ", Global Strategy Timeline", is the clearest early answer because it turns Perbov's situation into a concrete plot event. A useful checkpoint is the way the scene starts with They truly couldn't hold out any longer. and follows through with Some of the missing and unaccounted for, those whose bodies couldn't....
Chapter 199, ", New Blood of the Battle Group", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter turns that into something concrete by moving from After receiving the 1432 points of grace this month, Gu Hang now had... to Out of the 150 carefully selected teenagers, only three could be....
Chapter 276, ", Intercontinental Missile", is the clearest early answer because it turns Alliance's situation into a concrete plot event. The chapter gives readers a real answer by opening on He didn't need to hide in an air-raid shelter; the missiles wouldn't... and ending on At least fifty missiles launched an attack on them..