Despite Morrigan's reputation as "The Truth Teller" in future of the A Court of Thorns and Roses books.

Mor's powers have never been explained; they're subject to speculation even past A Court of Silver Flames, which centers around Nesta and Cassian's controversial storyline. Trying to puzzle together what her power could be is ittedly difficult. Since Mor is able to both lie and be deceived, her powers don't derive from truth or honesty. However, Maas often takes inspiration from many elements of Celtic mythology in her writing, and this connection could explain Mor’s power of truth.

Mor’s Power May Be Truth, But It's Not What It Sounds Like

Mor's Power Can't Be Too Obvious But We Haven't Seen Enough Yet

Throughout the ACOTAR series many different situations take place where Mor is described by the Inner Circle as "notorious" and "feared." Known for her skill on the battlefield and mysterious “Power of Truth”, Mor has a big reputation. However, Maas never dives deeper into the abilities that come with her 'Power of Truth' or what Mor is truly capable of. One thing that’s clear: the “Power of Truth” cannot be connected to Mor’s ability to lie or tell the truth, because she manipulates the truth multiple times throughout the series, one example being how how long Mor mislead Azriel about her feelings for him.

If Mor’s power is truly not connected to her ability to lie, it is certainly not connected to her ability to tell when she is being lied to. Proof of this is when the Inner Circle meets with the human queens to collaborate on a plan. Betraying and sabotaging the Inner Circle, the human queens completely lied to Mor’s face during the meeting, and she believed them. Mor’s “Power of Truth” has to signify something more significant than literal truth or deception, because Mor is easily fooled. Subtext from Maas and the Banshee theory suggest a reason for this.

Without a substantial connection between Morrigan's rumored "Power of Truth" and any logical abilities her power might grant her, Maas leaves a lot up to interpretation. This is how the Banshee theory takes root; Banshees are also known for their "Power of Truth" and yet, their powers are not at all connected to deception either. Banshees' powers are more complex. Banschee's battle screams are actually considered their source of truth, as a Banshee's scream is believed to turn the tides of war and reveal who will prevail in the end. Foreshadowing suggests this could potentially be Mor's power, too since there is nothing else to go off of in the text.

Foreshadowing From Eris Suggests Mor Has Ties To Other Significant Banshee Myths

Eris Insinuates That Ending Their Engagement Was For Reasons Mor Won't Reveal

Eris Vanserra is one of many A Court of Thorns and Roses characters that has been unfairly judged due to his complex history with Mor. Centuries ago, Eris and Mor were engaged and arranged to be married by their parents (against her will). Before the night Mor was sold to the Autumn Court she rebelled; she chose to lose her virginity to Cassian to take control of her autonomy while she could. Once Eris learned of this, Mor claims he ended their engagement in disgust. Out of fury, her family brutalized her and left her for dead on the borders of the Autumn Court; she was found with a note for Eris nailed to her womb.

Maas' choice of the word 'womb' is intentional and a huge context clue about Mor's backstory. The word 'womb' is the only word to describe an abdomen that has well-known associations and connections to motherhood, child-bearing, and fertility.

In ACOWAR, when Eris becomes a more involved character as heir of the Autumn court, he hints that there is more to the story regarding their broken engagement that only Mor can share. This implies that Eris can actually be benevolent, caring even, and he ended the engagement for Mor’s sake. Perhaps Eris is wearing a mask similar to Rhysand in ACOTAR, curating the image of a villain to protect Mor's secret from that night. If Mor's secret can explain why Maas specified the stab wound in her 'womb' it may connect tangible ties to this Banshee theory.

“I wouldn’t have touched you,” he said to Mor, who blanched again. 'But when you fucked that other bastard—' A snarl ripped from Rhys’s throat at that. And my own. 'I knew why you did it.' Again that secret smile that had Mor shrinking. Shrinking. 'So I gave you your freedom, ending the betrothal in no uncertain ....There are few things I regret. That is one of them. But … perhaps one day, now that we are allies, I shall tell you why. What it cost me.”

In Celtic mythology, Banshees are beautiful, often described as young women (like Morrigan) that become Banshees after the loss of a baby or infant. Initially, this description might not seem to match Mor perfectly, but the word “womb” being used by Maas is a very specific and peculiar choice of words to describe the nail in her stomach. Why wouldn't Maas use a more common word such as abdomen, stomach, or gut? Using the word womb, when paired with the fact that Mor had recently lost her virginity, poses whether her family caused her to lose a child, and she became a Banshee

Why The Morrigan As A Banshee In This A Court Of Thorns & Roses Theory Doesn't Work

Banshees and Morrigan Share Similar Powers But The Mythology Doesn't Line Up With The Previous Books

This popular ACOTAR theory poses that Banshees have a very specific power of truth that may appear reminiscent of Mor’s power. Banshees serve as a source of truth because, at the most pivotal moment of a battle, they’re known to scream and predict the true fate of the war. Their source of truth is used not for simple lies or deceptions, but rather to reveal a far more important truth: which side will be defeated and which side will prevail in battle. This could line up with the five previous A Court of Roses and Thorns books because Rhys claimed he'd "release Mor" if anything happened to Cassian or Azriel during battle.

Celtic mythology claims that the Banshee scream can turn the tides of a battle, and reveal the outcome of the war.

However, this theory doesn't exactly add up with the actual text from Sarah J Maas. It poses that during the next great battle, (which is growing closer with each installment), when all hope seems to be lost for Prythian, Mor could take Banshee form and scream to turn the tides of the battle. This theory could explain why Mor cannot sense deception and why Maas intentionally wrote that Mor's family stabbed her in the “womb”. Yet, if Mor is revealed to be a Banshee in the future of the series, it would go against some crucial elements of Celtic mythology.

Celtic mythology poses that traditionally, Banshees have red or silver hair, and while this doesn't represent Morrigan, there is also a much more glaring inconsistency. Banshees are disembodied spirits that have died and Morrigan is very much alive throughout the entire ACOTAR series. This theory might be catchy or fun, but overall it is far-fetched as Maas hasn't hinted towards this directly. Simply not enough is known about Mor to make these inferences yet, although we should know more soon in the A Court of Roses and Thorns television series.

The books of the A Court of Thorns and Roses series will likely delve deeper into Mor's character and explore her 'Power of Truth', but it is unlikely that she is a Banshee, as it just doesn't add up. Conflating the Banshee theory with the character of Morrigan is tempting to really make this theory work, but it's vital to the glaring differences between the two. Simply because Banshees are beautiful women, doesn't make Morrigan a Banshee. Inconsistencies between Mor's character and Banshees cannot be ignored just because Maas has yet to fully explore her full powers.