a more concrete and better look at tepeus naga/serpent form and alongside her partner kukulkan.
as kukulkan is more about the winds and was never depicted with wings i have decided to give 2 rows of feathers alongside his back that he could potentially be helpful in flight and a horizontal crest to give the depiction of the elongated skull he was said to have.

while tepeu being fire and lightning merely and thus ground based has the crest going down her back.