Unlike Lucifer, some angels never fell from heaven willingly – they were pushed.
Baring no sin, these betrayed angels would remain on Earth instead of Hell, becoming dragons; halos broken into horns, feathers charred to scales, and heavenly light breathed out as desperate fire.
This is why stories often depict dragons capturing princesses and hoarding treasure.
Dragons believe that if they act as guardian angels by “protecting” the princesses they capture, and “removing” humanity’s cardinal sin of greed by stealing treasure, then they would become angels again.