Stepsister wants a Deeper Massage - Part 1 of 4

After my stepsister and I traded massages that one Friday night, I haven't stopped thinking about how I could get my stepsister onto my massage table for a full body massage. She finally agreed but she wanted a much deeper massage than I even dreamed of. I had to break this up into 4 sessions because I thought I was done, but she kept wanting to go deeper. By the end of the 4th session, she was throbbing and couldn't take anymore.