I'm glad you are expanding the Mercy Universe. As enjoyable as Mercy Redux is, it's still a different pov of the very same events. Here we have NEW events, I'm curious to see what will happen next. Normally I tend to avoid fics that feature extra teams (in my personal head-canon, there is one RED team and one BLU team, and both of them have exactly 9 people each), but in this case the existence of other teams is such an excellent source of drama and conflict that I can't help liking it, I'm really looking forward to the next chapter. And anyway, accoding to the retirement epilogue, the characters still occasionally write to their old teammates, that's enough to make my head-canon happy. I wonder if the nice Engineer is Four's lover.