- “I pointed out of the window, to our family's necropolois, "I'm going to live!, I told her.”
Tessa was raised in Cumberland but grew disillusioned with her life and eventually elected to leave Nevarra entirely.
Tessa accompanies Marius on a mission to kill a Blood Mage in the town of Hercinia in the Free Marches. While Marius battles the mage, Tessa liberates her hostage, Buckingham, from his bonds. The next day while shopping at the Market, Tessa notices she is being followed. Tessa eventually returns to Marius, cheerfully announcing her tail before turning to confront her pursuer. The stalker introduces himself as Flavius, a slave in the service of Magister Illeneva. The Magister has learned of a group of blood mages sacrificing children to fuel uniquely powerful blood magic rituals in Tevinter and enlists Marius to destroy the group. Tessa travels to Tevinter alongside Marius to the site of the ritual, a set of ruins in the Valarian Fields just north of Minrathous. Upon arrival, Tessa is surprised to encounter Flavius himself, being escorted by a whole cohort of Tevinter soldiers, led by Radonis; Archon of the Imperium.
Radonis reveals he wants to hire Marius for an assassination of several cultists known as Venatori. Marius adamantly refuses until Tessa persuades him that it is pointless to rebuff the Archon. Tessa suspects that since Radonis has gone to such extraordinary lengths to conceal his involvement with these assassinations, he will likely kill Marius and herself afterwards to remove the final link back to him but concedes they still have no choice. Tessa assassinates Havian Sulara herself, while Marius disposes of another two targets. Tessa tracks the final target to a bathhouse where Marius can dispose of her. However, much to her surprise, Tessa walks in to discover Marius kissing the target; Calpernia. Realizing their shared past means Marius will never finish the assassination contract, Tessa flees along with Marius to the Frostback Mountains in southern Thedas. As Tessa and Marius dispose of another squad of mercenaries sent to kill them by Radonis, the duo stand dumbstruck as The Breach opens up above them.
In the months following the Breach, Marius and Tessa help fight off Demons spawning from the various Fade rifts while simultaneously attempting to evacuate as many civilians as possible. After one particularly dangerous battle on a nearby farm, Marius and Tessa retreat to a village to recuperate. Marius passes out from exhaustion, and Tessa retreats to the tavern. Finding herself alone except for a lone other patron, Tessa discovers the visitor is apparently searching for her and Marius. After a brief stand off, the traveler reveals she is not there as part of an assassination attempt, but has been sent to recruit the duo for the Inquisition.
Now part of the Inquisition, Tessa and Marius have been sent to the Hissing Wastes to deal with the Venatori excavating the ruins there. Unable to deal with the problem on their own, as the Venatori have reinforced their position since The Inquisitor's visit, Tessa asks Charter to send additional support. This support comes in the form of Dorian Pavus and some of the Bull's Chargers led by Krem. Their main target is a camp of fifty Venatori, too many for them to take head-on. While Dorian and Marius provide a distraction, Tessa frees the captive slaves; once all the slaves are clear, Rocky, the Chargers' sapper, brings the cliff wall down on the camp, killing the remaining Venatori. After parting ways with Dorian and the Chargers, Tessa and Marius return to Charter in one of the Inquisition's strongholds, only to find Sister Nightingale waiting instead, saying that the Inquisitor requires their assistance.
They arrive at Skyhold only to find that the Inquisitor and their army have already left for the Arbor Wilds. While Tessa and Marius are killing time in the Herald's Rest, they hear an explosion in the distance, and come out to find that Corypheus has reopened the Breach over Haven. The Inquisitor and the Inner Circle head to the temple of Sacred Ashes. In the meantime Charter, with whom Tessa has started a romantic relationship, explains that they are needed to clear a route up to the ruins of the temple to provide the Inquisitor with reinforcements. Sutherland's company is to go with them. Before they can depart, Charter takes Tessa aside and asks her not to die for Marius.
On the way to the temple, Tessa, thinking back on Charter's words, starts wondering what it is Marius needs her for. When they reach the caves, they find them filled with many demons, including a massive Pride demon. Shayd jumps on the demon's back with her daggers; Tessa, anticipating what will happen next, pushes her away and takes the shock meant for her. When the demon grabs her to finish her off, an enraged Marius rallies Sutherland's company and finally kills the demon by stabbing it through the mouth. Tessa realizes that Marius does care for her, even if he can't express it properly.They exit the caves with Sutherland's company to meet up with the Inquisition's forces. As they look up on the two dragons fighting overhead, they take satisfaction in knowing they helped save the world.