but I'm not sure how to realestically pair them lol.

Maybe Chrysalis is needing sustenance while on the run, feeling super-weak and vulnerable following her loss to King Thorax in the Changeling Kingdom. She finds herself near Ponyville, and sees a pony who she assumes would be easy to indoctrinate: Derpy. However, despite being able to assume a form that can create a quick bond with Derpy, shenanigans ensue when Chrysalis struggles to keep up with the mare's antics and clumsiness. During this time, Derpy shows her new friend nothing but the purest friendship, even allowing Chrysalis to stay in her home with her daughter Dinky. Because of that, Chrysalis is able to better understand the mare through time, and appreciate how dedicated she is as a single mother and delivery pony. And even when her strength is regained through Derpy's love, Chrysalis finds herself becoming more connected with her to leave so soon. In fact, despite her plans of domination, she can't help but feel certain... unconventional things about the clumsy mare~

7431675
You can't, but it's a ship, so don't worry about realism.

7431682
*grins* Yay that this forum is still alive.

7431680
Interesting.