My Sister

I've always been close to my sister but we're in a whole new place now. We're a year and a half apart and one night while the parents were out, we were fooling around online and hit some pron. It was a blowjob and she got turned on and I dared her to blow me. She thought it was sick and said no but kept watching anyway. The next was a girl getting eaten and that did it for her too. Neither of us are virgins but we don't have anybody serious either.
We ended up betting on something and if I won she had to blow me for 1 minute and if she won I had to go down on her for a minute. She won and I ate her and got her off.
We do a lot of betting now and whoever loses has to satisfy the other and we have full on sex with protection. Its the same if one of us just really needs it and thats usually me but sometimes her. The deal is nobody ever knows and never when the parents are here.