Theres this thing with...Omegas. Listen. While Omegas certainly weren't the strongest, they still had their little heriechy with other Omegas. Sort of.

What they would do, is they would sort of pseudo-mount another Omega. They would go up behind and either sort of doggy style lean over and mount or usually stand beside and press their hips to the others butt.

It was never done much. Not really too crazy just a 'I'm stronger/better/cooler/ more dominant than you'. A way of saying 'I'm dominant, you're submissive'. And usually, with society it was mostly forgotten.

But Lydia, your beloved Lydia, kept mounting you. It's like she was making it a point to consistently lean over you. Pin you up against things and press over you from behind. Its never sexual, no! She just keeps doing it.

You love her, but god is it making your instincts confused.