Disclaimer: I couldn't think of a way to do this in-canon in any real way, so it's kind of an AU style "what if?" kind of variation.
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Benezia slumped against the tank of the Rachni Queen, completely spent and badly injured. She looked up at her young daughter and the woman who had bested her who stood beside her. Both looked concerned and sympathetic despite the fact she had tried to kill them, especially the former.
"I cannot go on," Benezia said as her head sagged down. "You will have to stop him, Shepard."
The matriarch struggled to her feet and looked the human woman in the eyes.
"Hold on!" Shepard said urgently. "We've got medi-gel, maybe we can-"
"No!" Benezia interrupted. "He is still in my mind. I am not entirely myself. I never will be again."
Tears came to Benezia's eyes as she stumbled backwards. Liara's welled up as well. "Mother!" Liara said urgently just as Benezia's back made contact with the Queen's tank once more.
"Good night, Little Wing," Benezia cried to her daughter. "I will see you again with the dawn."
"No!" Liara yelled, and her body pulsed with blue light. Benezia glowed and shimmered, freezing in place. Before Shepard knew what was happening Liara had stolen a pack of medi-gel, run forwards and flashed her omni-tool over her mother's frozen form.
"Liara! What are you doing?"
"I can still save her, Shepard! I won't let her die now!" Liara said with conviction.
"Would she want this, Liara?" Shepard asked softly. "She said the indoctrination was too strong and that she'd never be the same."
"There might be a way. I'm not sure, it's just a theory I have. But I'll need to get her to med-bay on the Normandy fast."
Shepard looked at Liara sideways, her face etched with skepticism. They hadn't spent long together, but they had definitely grown close. Very close. Close enough for Shepard to know that look of determination on Liara's face and how strong it was. The Commander finally sighed gruffly in defeat and nodded. "You and Wrex back to the Mako with her," she ordered. "I will finish up here and met you at the vehicle as soon as I can."
A few hours later, after a direct encounter with The Rachni Queen and activating a neutron purge, Shepard found Liara in the med-bay with Dr. Chakwas and her mother. Benezia was restrained on a medical bed and appeared to be sleeping. The two figures regarding her looked at what looked like some kind of scan of Benezia's brain activity from what Shepard could tell. "What's going on, Doctor?" Shepard inquired.
"She received some serious injuries from your little scuffle on Noveria, but she's stable now," Chakwas said. "The main concern of course is the indoctrination. Judging from these scans it's pretty deeply set, and I would tend to agree with what Benezia had said about her recovery, or lack thereof. Liara here seems to think otherwise."
"You said you thought there was a way," Shepard said to Liara with a frown. "After seeing this do you still believe that?"
"I don't know," Liara admitted. "But I have to try. It's either this or death for her. I already lost her to Saren, I don't want to lose her entirely."
"Are you willing to do what is needed if it doesn't work?"
Shepard had a hard look and tone, and as much as the question and the way it was delivered hurt Liara she understood. Shepard couldn't risk the ship, the crew and the mission if worst came to worst. Deep down she knew that her mother may end up dying at her own hand if it all came crashing down. It still took her a while to answer as her gaze fell both somewhere and nowhere. "Yes. I am."
Shepard gave her a satisfied nod and then turned to Chakwas again. "Will those restraints hold her if the full force of the indoctrination kicks in?"
"I can't honestly say. She's a very powerful biotic, but she is still in a weakened state and the sedation will also be dulling her biotic potential. I still wouldn't leave her alone without supervision and a gun or two nearby in any case."
"Okay, so what's this theory of yours then, Liara?" Shepard asked curiously.
"It's based on a practice that's sometimes worked with asari who have memory loss or certain mental illnesses. Basically, some asari suffering such afflictions have been cured when another asari close to them has linked minds, just like Shiala and I did with you after your visions. Over time they gradually get rid of whatever is afflicting them and gain more of their true selves. By connecting with somebody who they know and love they have managed to piece together their memories again and return to who they are."
Liara sighed and looked at her mother sadly. "I just don't know if it'll work with Saren's indoctrination. We have no idea what we're dealing with here. It may be so deep I can't reach her. She could be right, and she may never be the same again."
"Will this put you in any danger?" Shepard asked with serious concern.
"Only if she has a violent outburst or something. It will be tiring and I'll need her to cooperate if it's going to work. If she can resist it like she did briefly on Noveria then it should be fine, and there's probably little point in trying if she's not really herself anyway. We'll both need to fight this together, from both sides."