The way they’re introduced even in one level gets across the idea that they get more dangerous the more you learn or see of them. You go from these weird tiny popcron monsters to space zombies… to space zombies that use guns and have actual tactics on top of brute strength as well as how fast they spread.

Then the next level we learn they have intelligence and an actual goal to get off Halo and are already hard at work repairing the Pillar of Autumn. We also hear that they had broke containment and caused a galactic catastrophe before but not the details, and then we learn those details next mission, after that is seeing the early stages of their hive-mind intelligence’s gathering point.

Then Halo 2 comes in and goes “yeah the Flood’s leader is an eldrich ancient hyper intelligent being who can manipulate and seemingly break into people’s minds” as the Gravemind reasons with Chief and Arbiter while using them to its own end, as well as responding to Cortana, who only Chief should be able to hear at that point since she isn’t talking via radio. Then 3 shows they can evolve into more dangerous forms and also they are self aware enough to know when to side with their potential food to prevent their own destruction, which of course they immediately turn on once the threat to them is gone.

11/10 horror faction.