The Ori aren't able to use their powers to control mortals because the Ancients would intervene, but the Ori needed a leader with power, one capable of leading their armies so Adria was created. After her birth, she was genetically altered to grow to adulthood at an increased acceleration, and was an adult within a matter of days. ("Flesh and Blood")
After the Free Jaffa Nation attempted to destroy the crew of an Ori warshp with the Dakara superweapon, Adria alone survived, due to the shield she possessed. She captured Dr. Daniel Jackson and Vala Mal Doran. She then revived one of the Jaffa to interrogate him and he told her the weapon that had killed her followers was on Dakara.Upon reaching Dakara, she destroyed the weapon but SG-1 was beamed off the ship by the Odyssey. ("Counterstrike"). After having discovered the location of the Sangraal, she implanted a dream into Vala to get SG-1 to come to Oric's planet. Once they arrived, she impersonated Orsic and offered to lead them to the Sangraal. When they came upon one of Morgan's puzzles that trapped Ba'al nd had to leave her ring in a treasure box, Jackson noticed the ring was of Ori design. Once at the caverns, SG-1 confronted her and she revealed herself. She then threatened to kill Lt. Colonel Samantha Carter if they did not help her get the Sangraal since she was unable to do so as the cave held a device which neutralized her abilities. She helped them get past the rest of the puzzles and reach the Sangraal but the Sangraal was a hologram which also caused the awakening of a Dragon, Adria realized that the dragon was the final test, and Jackson's realization that it was Ganos Lai who was the true guardian neutralized the dragon. However, upon returning to the Sangraal, SG-1 and Ba'al were transported to another planet via a teleportation set up by Ganos to further protect Merlin from discovery, forcing Adria to mentally examine the planet's DHD to determine their location. Eventually, Adria and her soldiers found the planet in question, where Jackson had the memories of Merlin downloaded into his mind. Adria attempted to kill SG-1, but Jackson gave them enough time to flee through the Stargate, leaving Daniel in Adria's hands. ("The Quest Part 1", "The Quest Part 2")
Adria had plans for Jackson, hoping to use the Sangraal to destroy the Ancients without having to risk the Ori themselves. Having seemingly convinced Daniel of the virtues of Origin, she eventually turned him into a Prior, so that he would be able to complete the device and use it against the Ancients. However, Daniel, with help from the consciousness of Merlin, resisted her efforts, partly helped by the fact that Adria was so determined to convert Daniel as she saw him as her only hope of converting Earth. He nearly completed the Sangraal, but allowed himself to be captured by SG1 so that they could shut down the wormhole currently blocking the Supergate. With their help, he attacked Adria and was able to send the Ori warshipcarrying the Sangraal through the Supergate. Adria herself later confirmed that the device was successful in neutralizing the Ori. However, Adria was not destroyed by the Sangraal, and she then sent another six Ori battle cruisers through the Supergate. ("The Shroud")
With the Supergate under control, Adria encountered Val on a planet She falsely claimed that the Sangraal failed in its attempt to destroy the Ori, and learned that Vala had fled Earth, as SG-1 believed that she was being manipulated by Adria using the Clava Thessara Infinitas to trap them. Adria and Vala traveled to the planetin question, only to find SG-1 already there and waiting, and it was revealed that Vala had allowed herself to be implanted with a false memory by the memory device. However, Ba'al arrived and kidnapped Adria, taking her as a host, claiming that he would order the Ori Army to leave the Milky Way galaxy. Ba'al managed to unleash his symbiote toxin into Adria. Dying, Adria used the time she had left to ascend. However, while Adria now possessed all the power the Ori gained from their worshipers in both galaxies- the loss of the other Ori meaning that she now possessed the entirety of the power that had once been divided amongst the entire Ori race-, it also meant that she could no longer take action on this plane of existence without inciting the wrath of the Ancients leaving the Ori army leaderless. ("Dominion")
After locating the Ark of Truth, Vala, Tomin, and Jackson were captured. There, Adria revealed herself to Vala. She confirmed that she planned to destroy the Ancients,and take over both galaxies, but declined to use the Ark, saying it just wasn't as "fun", and it also failed the generate the right 'kind of belief' that she could use to draw power. Vala also described her as a "spoiled brat with a God complex". She also confirmed the death of the Ori saying she was pleased as she now possessed all of their power. She was finally stopped when Daniel activated the Ark, severely diminishing her power. With her power now reduced, Morgan le Fay engaged her in eternal battle. ("The Ark of Truth")
[SG-1, Ba'al, and Adria are blocked by a wall of fire]
Ba'al: Why don't you do something? You're the Orici. You're supposedly possessed of significant powers. So snuff out the flame and get us on our way.
Adria: My abilities don't work that way.
Ba'al: Of course, how does that Earth saying go? "All flash, no photo?"
Lt. Col. Carter: Actually, it's "All flash, no substance."
Ba'al: I prefer my version.
Adria: Would you care for a demonstration?
[Ba'al stares her down]
Adria: [haughtily] Taking your life would be a waste of my time.
Ba'al: Which I suppose would be put to better use complaining.
Lt. Col. Carter: Oh, geez, why don't you two just get a room?
Adria: No! You can't take away my power!
Vala: I think... we just did.
Adria:: You will all burn in the fires of eternal damnation!
Morgan le Fay: Not if I have anything to do with it.
Adria: You're no match for me.
Morgan le Fay: [smiles] I am now