I personally have a head-cannon that after the minor Deity cabins were made a few of the cabins who had less people banded together with other cabins that have similar parents, for instance Janus, Hermes, and Hephaestus are all kinds trickster gods, or Hades, Nyx (if that happens), Thanatos, and Hecate are all darker deities and so there's cabins make bonds, sibling bonds, romantic bonds, maybe just someone you once met bonds but because the cabins are close they act closer to each other plus I think I speak for all of the Thanatos cabin when I say I'm in with horror movie night.