AU where Athena decides Erich is a failed experiment, so, using whatever means the writer prefers, she restrains Erichthonios and non-cons him into impregnating her a second time (since obviously Lahabrea isn’t up to the task)

Bonus points for Erich being absolutely terrified by the idea that it might work and trying to hold back his orgasm for as long as possible but Athena forcing it out of of him anyway.