- According to Nightingale's first team mate, Sunshrike, there are only the two members of this avian-themed team at any one time. One representing the "bird of light" and the other the "bird of shadow". This suggests they're legacy characters, with new women taking the roles in an alternating fashion, one a mentor, the other the learning sidekick. Given the age differences, it seems to be generational. Nightingale is the younger in the 80s with Sunshrike, and she gains experience and matures to become the elder in the 90s with Sunbird. There is also speculation a familial connection might be in play with who takes up the legacies.
- Sunshrike also thinks it wouldn't be allowed for them to have a cat as part of the team, hinting that some external agency may be involved with sponsoring this pair of avian heroes.