Soul O'Brien serves as a foil to Marcus, showing that those who claim to be "good" can become the very monsters they hunt.
Nathan discovers his gift is "Power Mimicry" (or a variation of his father's ability to take/use others' gifts), making him one of the most powerful witches alive.
This guide covers the climactic Season 1 finale (Episode 8) of The Bastard Son & the Devil Himself , detailing the major plot points, the high-stakes confrontation, and how the season concludes.
Gabriel and Annalisa fight side-by-side to hold off the Council's hunters. Annalisa continues to struggle with her "Decimation" power, ultimately using it to devastating effect to save Nathan.
The episode reinforces that Nathan is not "born evil" because of his father; his choices define him.