Zanzibar Hashtag was a technician who was a hostage of the Sycorax and was the next one to be executed.
The Seventh Doctor met her when she was in extreme pain. She deliberately infected herself by a genetically engineered executive-grade virus that she got by saving up. She had a key to the Blood Bank's vaults.
She started to fall in love with Shadrak, which was against company policy, as they bypassed the dating app on their devices. After coming back from the Sycorax ship, she was tricked by them into letting them into the vault.