Inception and History
Like other Nexus-8 models, Freysa was created by the Tyrell Corporation in 2020 in the aftermath of Eldon Tyrell's death in 2019. She was bestowed with a natural lifespan and given ocular implants to better recognize her as a replicant. At some point, her right eye with the serial number identifying her as a replicant was removed (presumably by herself) as she is seen without that eye in Blade Runner 2049.
At some point, Freysa served alongside Sapper Morton in the war on Calantha. After the Blackout and replicant prohibition, Freysa and those Nexus-8 replicants who could fled into hiding to avoid retirement.
Contact with Rachael
It was 2021 when Freysa was present for the birth of Rachael's daughter and after Rachael's death, her responsibility to hide the child and scramble the records to keep her from being found. Freysa also became the leader of a growing replicant resistance movement sometime between the birth of the child and 2049.
Events of 2049
Uncovering a Miracle
In 2049, Blade Runner K of the LAPD retires Sapper Morton and uncovers the buried remnants of Rachael, a prototype Nexus-7 and partner to former Blade Runner Rick Deckard. After analyzing the bones, it is deemed that Rachael had an emergency C-section and died during childbirth. Under orders from Lieutenant Joshi, K is to find and destroy all evidence of a replicant giving birth, including finding and retiring the child.
Freysa and the Child
Whilst K looked over the photograph's of Sapper's tree in downtown Los Angeles, Freysa ordered Mariette and other pleasure models to find out what K knew about the child. After a brief interaction with them, K decided to return to Sapper's for further investigation. Returning to Sapper's house yields a photograph of Freysa holding a baby; presumably Rachael's child.
Freysa and K
Upon waking, K meets Freysa, who offers K a place with her resitance to fight for replicant freedom. She also reveals that K is not the special child he thought he was, and tells him that he can still help. Since K led Wallace to Deckard, he could not allow Deckard to lead Wallace to Freysa and orders K to kill Deckard to prevent a collapse of the resistance movement.