I helped my stepsister with her homework and as a thank you she gives me a blowjob and lets me put my cock in her.

She asked me for help and as her task was a little difficult, as a thank you for my effort she started to suck my cock. I couldn't help it and it got really hard. I asked her if I could put my cock in her and she said yes but that I shouldn't say anything. It's been a long time since we had sex since she got a boyfriend.