hot take:
the BoF series is in chronological order.
that's why you see the dragon blood get weaker with each sequel.
in 1 and 2 you have straight-up dragons. 3 starts introducing weirder forms, including the warrior form which is very similar to 4 and 5's forms. 4's dragons don't even look like dragons. and 5 is literally all about how the dragon blood has thinned over the generations.