What will happen after Meredith and Dereks three week fling goes public? Will he choose Meredith or Addison??

What happened if Meredith got attacked and Derek was the one to find her. This takes place in between season 2 and season 3. This is kinda like a combination of Merder and Meredith's career. #1 in MeredithGrey (Thank you!!!! Love you all!)