Callida is a member of the London Enclave. Because of this, Callida attended Enclave meetings regularly and often supported her niece Charlotte when others doubted her, though she does not think much of her husband, Henry, even pointing out that Charlotte did all the work her husband should be sharing.
1878 was a particularly big year for all of them. During a meeting at the London Institute in June, which Tessa Gray, Jem Carstairs and Will Herondale were eavesdropping on, Will claimed that Callida once propositioned him and that he had declined because she frightened him, although neither Jem nor Tessa believed him.
She was also present at the "Council massacre". The meeting was called by Consul Wayland, requiring all Shadowhunters to attend. There, Wayland accused Charlotte of being incompetent and hysterical, and emotional because of her pregnancy, and announced that Charlotte was relieved of her position as head of the Institute. Callida stood up against him and defended Charlotte. Mortmain's automatons soon broke in and attacked the mostly unarmed and unprepared Shadowhunters. It is unknown if Callida survived or not.
Callida is a proud and imperious woman, quite aware of the power of her family. As confirmed by Jem, Callida liked to tell people what to do, while she always did whatever she wanted.
Callida is tall, nearly six feet in height, with powder white hair usually wound on the top of her head. She looked as if she was well into her sixties, though she possessed a regal presence about her.