Replacing Teddy

I 24 came home early my parents were away, I heard soft moaning coming from my sister's room. Thinking she might be ill I went to see if she was okay, she 21 was. She was masturbating herself grinding her pussy against her teddy bear. I got an instant hard-on seeing my naked sister, she was shocked at getting caught riding her teddy bear. But she recovered and then focused on the bungle in my pants. She wanted to see my hard-on and said I've seen her so it's only fair I show her my cock. She liked what she saw and still being horny asked me to fuck her. She is on conception so no worries about babies, so I agreed and we became lovers, of course we didn't stop at just the once and every time were alone, we fuck. Poor teddy is now just left in the cupboard.