History
Sarah was conceived when her mother Kathryn O'Brien and father Frank Castle first slept together shortly after her mother had saved her father's life.[1] Her mother did not tell Castle that she had conceived and given birth to their daughter and instead left Sarah to be raised by her aunt and uncle while she sought out revenge in Afghanistan where she would then die.[2] Sarah was kidnapped as an infant by the mercenary Barracuda who planned to torture and kill her in front of her father[3] as revenge for Castle having beaten and harmed Barracuda some time before.[4]
Sarah was held captive for a number of days until her father faced off against Barracuda and ultimately managed to kill him after an arduous battle.[5] Sarah was then returned to her aunt by her father who believed she was safer there with no idea who her father was and with no one else knowing about him either.[5]