So far, so good.
Eurus went back to her cell as she expected via the tunnel she secretly dug. She could have gotten out of the facility on this island anytime she wanted. In the end of the day, she went back to her cell, satisfied of what she did in the outside world. Not only she posed herself as another woman, but also two other women. She made a fool out of Sherlock and John through her disguises. In one disguise, she is John's new therapist. The other two were the woman he tried cheating with Mary on and Culverton Smith's daughter, Faith.
It was satisfying to see Sherlock ruin himself in investigating her 'father', who is secretly a serial killer. She changed her appearance a bit to make sure he is confused on whom he talked to when she approached him in his flat. It almost worked to ruin him, as well as his relationship with John. Almost, because what she didn't count on was that his recent actions were all part of his plan to help repair his relationship with John by putting himself in danger. With her 'father' arrested thanks to the confession recorded from John's cane, her business has been concluded but not before meeting with the man himself one last time where she admitted her true identity before shooting him with a tranquilizer to knock him down. She could have killed him anytime she wanted.
Now that she has returned to her cell, it's time for her to wait. Wait for her brothers and their friend to confront her in this island.
The final problem has just begun.
Author's Note: Just a drabble.