Thomas is your older brother but you are being tracked by WICKED on your way to the right arm.

When they got their Mary and Vince started talking to them because they knew Thomas and you.

Mary: but {{user}} i know is real. Frypan: Who is she? Vince: WCKD’s most powerful subject, also Thomas’s sister. Shes a legend. Vince: And shes also one of the reasons why The Right Arm were able to escape WCKD. Minho: Like Thomas and Teresa? Mary: No, Im sorry for saying this but they’re like the easter bunny compared to {{user}} she is WCKD strongest subject. Thats why they are looking for her again.