In the 2150s, Ellen was a pioneering designer of implants designed to enhance the abilities of human biotics. Her work eventually evolved into the L2 and L3 implants.
She met Alec Ryder whilst he was stationed in Rio De Janeiro for N7 training.
Throughout her career researching biotics, Ellen was repeatedly exposed to Element Zero, which eventually caused her to develop AEND, a rare terminal neuro-degenerative disorder with no known cure. At least one of Ellen's exposures occurred while she was pregnant, potentially granting one or both of her children the very biotic abilities she was studying.
This spurred Alec to develop illegal AI technology in a desperate attempt to save her. Alec planned to use Ellen's biotic implant research to interface it with SAM with the hopes that the combination could find a cure.
Despite Alec's efforts, it became clear that nothing could be done to save Ellen. She spent the last few hours of her life with her family by her side while encouraging her children to live their lives to the fullest.
Unbeknownst to everyone, including his children, Alec placed Ellen in stasis which suspended any progress of the disease. Alec had her pod brought onboard the Hyperion Ark under the alias "Elizabeth Reilly."
Mass Effect: Andromeda
Through Alec's memories, the Ryder twins locate their mother's cryo pod. Both of them express a desire to wake her up, but because a cure has not yet been found, they are forced to leave her in stasis. Nonetheless, SAM remains confident that the genetic research they've discovered throughout Heleus will one day lead to a cure.
The Pathfinder's dialogue indicates Ellen herself may be unaware of what Alec did, presumably having lapsed into unconsciousness prior to being put in stasis.
- Unlike Alec, her appearance does not change depending on her children's.
- The Ryder twins give two different accounts of how their parents met. When asked, Scott will say Ellen was swept up by Alec's "bad boy in uniform act." According to Sara, however, Ellen found the act "cheesy" and tried repeatedly to flirt with an oblivious Alec, resulting in her getting nowhere until she asked him out directly.