HELP! My novel is being HIGHJACKED by a side-character_IWSG Post

 

Batman has Oracle. James Bond has Q.

McCord has Lady Lovelace. Ada Byron.
She appeared in his first novel, RITES OF PASSAGE, set in the Bermuda Triangle of 1853.
https://www.amazon.com/dp/B09TDW4XN
Then with unladylike persistence, Ada elbowed her way into its sequel, ADRIFT IN THE TIME STREAM.
https://www.amazon.com/Not-So-Innocents-Abroad-Roland-Yeomans/dp/1530302722/
Ada found her way into two of McCord's 2 Steampunk adventures with Mark Twain and ll year old Nicola Tesla.

https://www.amazon.com/dp/1519375794/
Her skill at math, puzzles, and algorithms helped McCord contend with star-gods in his 1895 Egyptian fantasies.
https://www.amazon.com/Legend-Victor-Standish-1/dp/1508804540/

She even wormed her way into half of his son's adventures!
Have you ever had a character in your books take on a life of her own?