Yes

It was around two a.m. when you woke again, from the room being cold. There had been a black out during the night, and the heat lamps were dead. A quick glance at Darcy, revealed she was still asleep but her blankets had slid down to her waist. Therefore she was cold and semi in the 'Hibernation' state.

Carefully, you remove the blankets and wait til Darcy was fully asleep before turning her over and laying her flat. You then pull off her pants and underwear, before spreading her legs Spread Eagle. Gripping her hips, you enter her anus and start to move. As she was loose from when you fingered her; it was easy.

She started to pant in her sleep, and you pick up the pace a bit. Soon you released deep inside her bowels, and then pull out. "That was great~," You think. "I hope the blackout lasts a bit longer."

Surprisingly, it does. The whole mid-morning there was no heat, what-so-ever. You used this opportunity to examine Darcy's womb again; tying her wrists to the head board and spreading her legs fully out. You trace her pussy with one finger, then make the speculum open her all the way. Her womb entrance is in full view...and shudders when you touch it with a Q-Tip before you move it in and out of the womb.

Darcy moans, and you put the Q-Tip aside before removing the speculum and inserting a vibrating dildo into her folds and turned it on.

You then slid into your hybrid sister's bowels again; pounding over and over. Her warm insides clench around your rod and seem to pull you deeper in. Darcy is soon panting, and climaxes after you do. However, it got her temperature slightly back up. So you hurried and cleaned up and untie her, before she finds out what you did.