Katriel was hired by Severan, through her bardmaster in Val Chevans,^[2] to seduce Prince Maric and betray him by leading him to capture at the battle of West Hill. However, she soon started to have feelings for him—wondering if she wasn't falling in love with Maric. Even so, she was duty-bound as a bard; she still betrayed Maric's army and caused a terrible defeat for the rebels − more than half of their army was slaughtered that day. During the battle, Katriel learned that King Meghren, during one of his typical rages, ordered that Maric to be left to die in the battle instead of merely captured. Though she protested the change in her orders while meeting with Severan's messenger, the latter decided that her contract had ended and attempted to kill her, only to be killed instead. It was at that moment that Katriel decided to switch sides and rescue Maric. If it wasn't for her help, not only would Maric have died, but also Lady Rowan and Loghain, who were outnumbered and gravely wounded by Orlesian soldiers.

Katriel tried to reveal her true identity and past to Maric during their journey through the Deep Roads, but Maric cut her short, explaining that whatever her past, it didn't matter anymore because she had saved him and his friends, guided them through the Deep Roads, and allowed him to discover true love. Loghain and Rowan found her behavior suspicious, but could not prove she did anything wrong.

At last, Katriel decided to confront Severan to cancel the contract that was binding her to him until she completed her task. Severan argued that a contract with a Bard could not be voided until the task was completed; she retorted that when he changed the terms—killing Maric instead of capturing him—the contract was de facto voided. She could have killed Severan on the spot, but her honor—unusual in the workings of the Grand Game—prevented her from doing so. She instead crippled him with poison to cover her escape, and advised Severan to leave Ferelden before his association with Meghren got him killed.

Loghain suspected something similar. He and Rowan had Katriel followed that night; their scouts then witnessed Katriel entering the Royal Palace. Katriel knew she was followed, but nevertheless decided to go back to Maric and confront him with the truth, trusting his judgment with her life. She was so filled with regret for betraying him that she was willing to die for her actions—especially since she had, in fact, fallen in love with Maric. To prove her love for him, Katriel left an envelope waiting to be found by Maric, explaining her regrets and describing how to defeat Severan.

Loghain confronted Maric with the fact Katriel had worked with Severan, without telling Maric she had left his service and was now a wanted woman. Loghain did this to make Maric understand what it means to be a king—that the right thing is not always the good thing, and not always what the king's heart wants. Unaware of her decision to leave Severan's service, Maric killed Katriel in blind rage, realising too late he hadn't wanted to do it and not finding her explanatory letter until after her death. Although he claimed that the truth "doesn't change anything" when informed of it by Rowan, Maric would regret his part in Katriel's death for the rest of his life.