Dr. Barbara "Bobbi" Morse made her first ever appearance in the comic book issue Astonishing Tales #6 on June 1971. She was depicted as a brunette variation of Jean Grey---Messed up telepathy and fearful that she'll murder Kevin Reginald, Lord Plunder aka Ka-Zar. She told his Maid and his Butler that. On Astonishing Tales #7, she still had brunette hair, the messed up telepathy is gone and now she wants to travel to the Savage Land, but needed the Maid and the Butler to tell her exactly where Ka-Zar was located. On Astonishing Tales #8, she departed from Za-Zar's English mansion and flew by airplane with her fiancé Paul to the Savage Land. The brunette hair turned blonde without explanation. It turned out that she was a S.H.I.E.L.D. agent who could've figured out where Ka-Zar was located by United States Government espionage computer tracking device rendering the Maid and the Butler useless.
Now no longer fearful that Ka-Zar will die (Possibly by her own hand), she only needed a second rate Tarzan wannabe to help her contain Man Thing (Don't ask). Paul is discredited, the wedding engagement called off before he's killed. Keep in mind that there was literally nothing in previous issues of the comic book series Astonishing Tales that even vaguely indicated that Dr. Barbara "Bobbi" Morse's fiancé Paul was a lunatic. Anyway, Paul dies and is never ever seen again making him one of the most thoroughly dead comic book characters ever. That made it possible for Dr. Barbara "Bobbi" Morse to fall in love with Kevin Reginald, Lord Plunder aka Ka-Zar. The romance ended when Ka-Zar moved from Astonishing Tales to the Ka-Zar the Savage comic book series.
Dr. Barbara "Bobbi" Morse waited until the comic book Marvel Super Action #1 in 1976 before she got her first ever colorful action costume super-suit. She was named the Huntress back then, but it was changed to avoid comparisons to Helena Rosa Bertinelli aka Helena Wayne aka the Huntress (Half sister of Damian Wayne (Same father, but different mothers) daughter of Selena Kyle aka Catwoman and granddaughter to Carmine "The Roman" Falcone). Dr. Barbara "Bobbi" Morse called herself Mockingbird instead to avoid copyright infringement lawsuit with DC Comics. However, DC Comics also has a character named Mockingbird (Born male) who leads the Secret Six (Not to be confused with the Spiderman comic book series super-villain team the Sinister Six). Anyway, Dr. Barbara "Bobbi" Morse fought crime in her street clothes exclusively when she dated Ka-Zar. She wore her colorful action costume super-suit when she hung out with Hawkeye. She joined the Avengers. She dated Clint Barton aka Hawkeye before the two got married. Dr. Barbara "Bobbi" Morse aka Mockingbird died. She came back to life. She divorced Clint Barton aka Hawkeye. They started dating, but refuses to remarry.
And now Dr. Barbara "Bobbi" Morse aka Mockingbird is being played by Adrianne Palicki starting in the second season of the television series Agents of S.H.I.E.L.D.. Life doesn't end in divorce court, but rather life continues for Dr. Barbara "Bobbi" Morse aka Mockingbird as a single woman. Of course, comic book continuity and movie/television series continuity are two separate entities. Mockingbird and Hawkeye has yet to date or marry for a first time in the movie/television series continuity so there is a chance to erase past mistakes instead of revisiting past mistakes as a substitution for religion.