At Sarah's request to run away you didn't know what to do... the animalistic instinct, increasingly stronger, made you think of staying there, of completing the transformation, perhaps soon mating with Martha, now completely an ass. Your huge transformed penis hadn't hardened yet, but if you got a little closer to Martha, it probably would.
Instead, the rational part still in you, diminishing, made you think of listening to Sarah, of perhaps looking for her friends, even of running away. As an electric shiver began to form above your ass, you found the strength to speak to Sarah: "How....how....how did you not changeeheaw" with the last word sounding like a bray.
"I don't know, I don't know"....said a disconsolate Sarah...."Suddenly my friends started to feel sick, some of them grew a pair of ears....and Bea... .and Bea....her face stretched into a snout....it was terrible....I did nothing, I stayed there for minutes, then I ran away looking for help....many they are changing, I don't know why I don't....".
In those same moments, the shiver above your butt had even become pain, it didn't take long to understand what was about to happen...