Guoba's video on Robin Summeretto kit and recommended teams he gives for Mydei
He reccommends Mydei, Cyrene, Cerydra, Srobin or Mydei, Cyrene, Mblade, SRobin.
Just thought I'd clip the section of the video about Mydei and Srobin. Mainly Srobin is just a bonus rmc. I'd recommend to watch the full video if you're interested in pulling for her. No you def don't need Hyacine to run Srobin with Mydei. Its recommended to run srobin with Cyrene tho cause mydei usually wants Cyrene. For build information on srobin go to 11:18 on the video linked below.
Link to video: https://www.youtube.com/watch?v=Rf_bLHedFbM