Shiala

Shialla is an asari, a powerful biotic and former follower of Matriarch Benezia. Commander Shepard's team encounter her on Feros.

Along with many of Benezia's followers, Shialla accompanied the matriarch aboard Sovereign as Benezia tried to guide Saren Arterius down a gentler path. When Benezia failed and became indoctrinated, Shialla also came under Saren's thrall. She willingly served him and accompanied him to Feros, where Saren encountered the Thorian and discovered that the immense, ancient alien plant had the Prothean Cipher he needed to understand the vision from Eden Prime. Shialla was 'sacrificed' to the Thorian and absorbed by it, sharing a single consciousness. She then used her biotics to gain the Cipher, which she transferred to Saren's mind. He then abandoned her to the Thorian and ordered the geth to destroy it.

When Shepard's team arrived, the Thorian was somehow able to create 'clones' of Shialla which served to communicate with Shepard. These clones were also biotics who attacked Shepard's squad as they tried to wipe the Thorian out. After destroying the Thorian, Shialla was freed and was fully herself again. She told Shepard of Saren's actions and explained about the Cipher. Knowing the vision was the key, Shialla touched Shepard's mind and directly transferred the Cipher. She then asked to be allowed to go to the Zhu's Hope colony and help them rebuild as penance for what she had done.

Shialla is the only individual who has managed to completely overcome Sovereign's indoctrination. This is likely because she was linked directly to the ancient Thorian and 'indoctrinated' by the plant being in turn. After the Thorian died her mind was her own again.