This theory explains why Mat is currently in no danger from any Seanchan due to his kidnapping of Tuon. The theory is based on events in Crossroads of Twilight, so if you aint read it yet, STOP READING NOW.

I believe that Mat is protected from Seanchan retribution by the promises he and Tuon have made to each other. As long as Mat keeps the promises he made to her and Selucia, Tuon will not expose him as his kidnapper. Anyhoo, here's my evidence for this idea.

The first promise that Mat makes to Tuon (through Selucia) is just after Mat has just claimed Tuon as his wife. Selucia enters all distraught like and to calm her down, Mat says

*** (WH Ch 31, “What the Aelfinn Said)

“Be easy, Selucia,” Mat said in soothing. She was not looking at him, but made calming gestures anyway. In none of his memories could he find a way to deal with a hysterical woman. Except to hide. “No one is going to be hurt. No one! I promise you. You can be easy, now.”

For some reason, consternation flashed across her face, but she settled to her knees and folded her hands in her lap. Suddenly, all her fear vanished, and she was as regal as ever she had been. “I will obey you, so long as you do not harm my mistress. If you do, I will kill you.” ***

It is my belief that the first sentence Selucia says is an order from Tuon (finger waggling = “obey the toy!”), which is why fear flashes across Selucia's face then disappears. This to me is Tuon accepting that Mat had promised not to hurt anyone. Which is why at the city gates, she didn't raise the alarm (COT, ch 1, Time to be Gone – it's a flashback bit, the quote is too damn long).

Mat's other promises to Tuon come about the first time he confronts her in her wagon-prison. This is the first conversation they've had since leaving Ebou Dar. (Mat: ***He had stayed away, after sticking her into that wagon, to give her time to settle down and collect herself. ***) The meeting didn't start too well (throwing dishes – such a great cliché! lol) and Mat promises stuff while trying to explain himself.

*** (COT Ch 3, Fan of Colours)

“I couldn't leave you behind to raise an alarm,” he went on patiently. That was true, as far as it went. “I know Mistress Anan has explained it to you.” He thought about saying he had been babbling from his nerves when he said she was his wife – she must think him a complete looby! – but it seemed best not to bring it up again. If she was willing to let the matter lie, all the better. “I know she's already told you this, but I promise no one's going to hurt you. We're not after ransom, just getting away with our heads still attached. As soon as I can figure out how to send you home safe and sound, I will. I promise. I'll make you as comfortable as I can until then. You'll just have to put up with the other.”

Tuon's big dark eyes crackled, heat lightning in a night sky, but she said, “It seems I will see what your promises are worth, Toy.” At her feet, Selucia hissed like a doused cat, her head half-turning as if to object, but Tuon's left hand wriggled, and the blue-eyed woman blushed and went silent. The Blood used something like Maiden handtalk with their upper servants. Mat wished he understood the signals. ***

Tuon's reply here is key to this theory. It seems obvious that Tuon thinks that keeping promises are important. I think what she says is Tuon weighing up the promises Mat has made, against his shortcomings (rudeness, telling everyone she was a thieving servant). After more banter, Tuon speaks of promises:

*** (COT, later in same chapter)

“I cannot say what I will do after returning to Ebou Dar, Toy. I have not decided. I may have you mad da'covale. You are not pretty enough for a cupbearer, but it might please me to have you for one. Still, you have represented certain promises to me, so it pleases me now to promise, as well. So long as you keep your promises, I will neither escape nor betray you in any way, nor will I cause dissension among your followers. I believe that covers everything necessary.” This time, Mistress Anan gaped at her, and Selucia made a sound in her throat, but Tuon appeared not to notice either. She just looked at him expectantly, waiting on a response. ***

*** (later in same chapter)

Mat did not know what to say or do. Without thinking, he spat on his palm and offered his hand as if stealing a bargain on a horse.

“Your customs are... earthy,” Tuon said in a dry voice, but she spat on her own palm and clasped his hand. “ ‘Thus is our treaty written; thus is our agreement made.' What does that writing on your spear mean, Toy?”

He did whimper this time, and not because she had read the Old Tongue inscription on his ashandarei. A bloody stone would have whimpered. The dice had stopped as soon as he touched her hand. Light, what had happened? ***

In the next quote Thom has entered and mentioned that the public does not know that Tuon is missing, as Egeanin said.

*** (later in same chapter)

So Egeanin had been right. It still seemed impossible. And it did not seem at all important compared to the dice stopping. What had happened? He had shaken hands with Tuon, that was all. Shaken hands and made a bargain. He meant to keep his side, but what had the dice told him? That she would keep hers? Or that she would not? For all he knew, Seanchan noblewomen were in the habit of marrying – what was it she had said she was going to make him? – a cupbearer – maybe they married cupbearers all the time. ***

So Mat and Tuon have made a bargain (which must be important to the pattern – the dice in Mat's head seem to think so):

Mat has promised not to hurt Tuon, to see her safely back to Ebou Dar (ASAP) and also he has promised to keep her comfortable. (NOTE: these promises also extend to Selucia.)

Tuon has promised that SO LONG AS MAT KEEPS HIS PROMISES, she will neither escape nor betray him, and she won't cause dissension in Mat's “followers” (as she calls them). The latter meaning she will not break apart Mat's team so that they can betray him.

The important thing with Tuon's promises is they are conditional – she will only keep them if Mat keeps his. But what do WE know about Mat and his promises? Consider Mat's promise to Rand about retrieving Elayne from Salidar:

*** (LOC, ch 39, Possibilities)

“I think he made a promise,” Egwene said simply, and Nynaeve nodded. Slowly, reluctantly, but she nodded. Elayne looked lost, of course; she did not know him. “Elayne, Mat does exactly as he pleases; he always has.”

“No matter how many turnips he had to peel for it,” Nynaeve muttered, “or how often he was switched.”

“Yes, that is Mat,” Egwene sighed. He had been the most irresponsible boy in Emond's Field, maybe in the Two Rivers. “But if he gives his word, he keeps it. And I think he promised Rand to see you back in Caemlyn, Elayne. You notice he retreated to asking me,” in a way he had, “but you he never changed a hair on. I think he'll try to stay as close to you as your beltpouch. But we won't let him even see you unless he does as we want.” She paused. “Elayne, if you want to go with him, you can. To Rand, I mean. As soon as we squeeze all of the good out of Mat and his Band.” ***

There are other quotes dotted throughout the series that imply that Mat will take wounds before breaking his promises. But also, we have a quote in COT that suggest that Tuon will also never break a promise. Egeanin says of Tuon:

*** (COT, ch 29, Something Flickers)

“She gave her word, Bayle,” Egeanin said. “Her word. She will not break that, ever.” Egeanin sounded absolutely convinced. More convinced than Mat was, anyway. But sometimes a man had to take a chance. Even if he was wagering his neck. He had promised. And he did have his luck. ***

Also considering what we know about Seanchan culture, to break a promise results in you losing Sei'taer, you would become Sei'mosiev. So Tuon also will not break her promises. But, Tuon does not know about Mat's honesty in promising stuff, so IMO a large part of the courting process is to Tuon a time to test Mat's honesty.

Up until the end of COT, Mat has kept all his promises, but from Tuon' POV, there have been a few near misses. This has resulted in Tuon being in situations where she could betray Mat, and consequently the dice in Mat's head start rolling. Then Mat ends up keeping his promise and Tuon decides not to betray Mat, then the dice stop rolling.

The first time Tuon tests Mat's promises is when she asks to go for walks. So far Mat has obviously kept his promise not to harm anyone, but there is also the comfort issue.

***(COT, ch 28, A Cluster of Rosebuds)

“I have kept my word, Toy,” she drawled as he was replacing the stones in the bags. “No attempts to escape, no attempts at betrayal. This is confining.” She gestured around at the interior of the wagon. “I wish to take walks. After dark will do. You may accompany me.” Her eyes touched the cluster of rosebuds, then rose to his face, “To make sure I don't run away.” ***

Mat agrees and the two begin taking walks after dark. In Tuon's mind, this is Mat keeping his promise to “make you as comfortable as I can” (from ch 3).

Later Tuon again displays loyalty to protecting Mat (keeping her promise not to attempt escape). This occurs at the end of ch 28. Luca's circus is crossing the Eldar and large amounts of Seanchan (soldiers and farmers) are about. As they cross the river, Mat sees Tuon sitting outside on her purple wagon (with her cloak hiding her face). The dice start rolling, but long story short Tuon does not attempt escape. That night, Tuon again tests his promises:

*** (COT, ch 28,)

He made sure all the Seanchan stayed in their wagons that night, and the Aes Sedai, too. Nobody had seen any sul'dam or damane that Mat knew, but the Aes Sedai did not argue for once. Tuon did not argue, either. She made a demand that sent Setalle's eyebrows almost to her hairline. It was phrased as a request, in a way, a reminder of a promise he had made, but he knew a demand when a woman made one. Well, a man had to trust the woman he was going to marry. He told her he had to think on it, just so she would not start imagining she could have anything she wanted out of him. He thought on it all the day that Luca put on his show, thinking and sweating while as many Seanchan as not came to gape at the performers. He thought on it while the wagons wound eastward through the hills, moving slower than ever, but he knew what answer he had to give.

On the third day after leaving the river, they reached the salt town of Jurador, and he told Tuon that he would. She smiled at him, and the dice in his head stopped dead. He would always remember that. She smiled, and then the dice stopped. A man could weep! ***

Okay, we know that what Mat agreed to was going to Jurador with Tuon and Selucia to buy material to make clothes, another part of making Tuon more comfortable, as Mat promised. If Mat did not agree, it would have been breaking a promise, and that would have destroyed the bargain they made. If that happened, Tuon would have done the Light knows what – escaped, called down the entire army on Mat, whatever. But since he agreed, Tuon still will keep their bargain. So they bought dresses and all was well!

Lastly (and this one is a little cryptic) we have Tuon testing Mat's promise to see her safely back to Ebou Dar. We have just had the revelation from Egeanin (who has been stabbed) that sul'dam can also channel. Mat is giving orders before running off to kill the sul'dam Renna (who would surely betray him to the Seanchan authorities).

***(COT, ch 29, Something Flickers)

“Juilin, leave all the gold for Luca except one good purse.” Maybe the man could bribe his way clear, once the Seanchan saw he did not have their Daughter of the Nine bloody Moons. “Gather everybody and ride out as soon as you can. Once you're out of sight of the town, take to the forest. I'll find you.”

“Everybody?” Sheltering Thera with his body, Juilin jerked his head toward Tuon and Selucia. “Leave those two in Jurador, and the Seanchan might stop with getting them back. It might slow them down, at leat. You keep saying you're going to turn them loose sooner or later.”

Mat met Tuon's eyes. Big dark liquid eyes, in a smooth expressionless face. She had pushed her hood back a little, so he could see her face clearly. If he left her behind, then she could not say the words, or if she did, he would be too far away for the words to matter. If he left her behind, he would never learn why she smiled those mysterious smiles, or what lay behind the mystery. Light, he was a fool! Pips danced a few impatient steps.

“Everybody,” he said. Did Tuon nod slightly, as if to herself? Why would she nod? “Let's ride, he told Harnan. ***

Mat decides to take Tuon with him rather than leaving her behind, at least in part confirming his promise to see her safely back to Ebou Dar. How could Mat possibly see Tuon home safe and sound if he is not with her to make sure she is safe? IMO Tuon's nod is in her mind something like, “oh good he has keeping ALL of his promises,” although there's probably more too it than that (like love, perhaps?).

Mat later returns from killing Renna and Tuon has clearly taken control.

*** (Crossroads of Twilight Ch 29, Something Flickers – Luca is speaking)

“Look what the Lady gave me!” Snatching open one of the cupboards, he pulled out a folded paper that he held reverently in both hands. It was thick paper, and white as snow; expensive. “A warrant. Not sealed, of course, but signed. Valan Luca's Grand Traveling Show and Magnificent Display of Marvels and Wonders is now under the personal protection of the High Lady Tuon Athaem Kore Paendrag. Everyone will know who that is, of course. I could go to Seanchan. I could put on my show for the Empress! May she live forever,” he added hastily, with another bow to Tuon. ***

Shortly after Valan says this, Tuon says to Mat:

*** “I did make specific mention of who is not under my protection, Toy.” Tuon took a bite of pastry and delicately brushed a crumb from her lip with a finger. “Can you make a guess whose name heads that list?” She smiled. Not a malicious smile. Another one of those smiles for herself, amusement or delight in something he could not see. Suddenly, he noticed something. That little cluster of silk rosebuds he had given here was pinned to her shoulder.

Despite himself, Mat began to laugh. He threw his hat down on the floor and laughed. With everything, all his efforts, he did not know this woman at all! Not a bit! He laughed until his ribs hurt. ***

So Mat is not protected by the warrant given to Luca. The quotes do not say it outright, but the implication that Mat's name “heads that list” is so strong that it may as well be proof. At first glance this looks like Tuon has written the order so that in the event of Seanchan becoming aware of her presence, Mat (and whoever else is not under personal protection) will be subject to Seanchan justice for kidnapping and a bunch of other crimes. But I do not think it so.

Conclusion:

By now, IMO Tuon is almost 100% sure that Mat will keep his promises. She has tested this a number of times, the first time when leaving Ebou Dar and being stopped at the gates (COT ch 1). Other times is when she asks for night walks and dresses (COT ch 28, 29). also when she is riding the wagon when crossing the Eldar (ch 28) – Mat could have panicked and harmed her, but did not, thus keeping promise. Lastly the safety one just mentioned (ch 29). So by now Tuon has every reason to trust Mat. For this reason I think it was now that she decided to act and taken control of the situation. So she is now in a position to reveal Mat to the Seanchan authorities as her kidnapper, but she will not – she has promised she will not, AS LONG AS MAT KEEPS HIS PROMISES TO HER.

This means Mat is in no danger from the Seanchan. Mat has promised a few things and so far has kept those promises. So long as Mat continues to keep these promises, Tuon has promised not to betray him in ANY WAY (see above quote from COT ch 3). This includes not telling the Seanchan that Mat has freed 3 damane. This includes not telling that Mat has freed a da'covale to the High Lady Suroth. This includes not telling the Seanchan that he kidnapped her. So Mat has a sure-fire protection from Seanchan justice here – just keep his word and he's free.

Other stuff – try not to judge this next stuff as it aint really part of the theory.

Who else is on Tuon's protection list, and who is like Mat and not protected? This is irrelevant as long as Mat keeps his word, since if any one member of Mat's party is revealed as a criminal, then Mat is also in the shlitt. So Tuon must protect them all so long as Mat keeps his word.

Another implication of this theory is that maybe Bashere has organized a meeting with the REAL Daughter of the Nine Moons – and Mat is there with them. We can not rule this out because we have no idea when the last 2 pages of the book (when Bashere tells Rand of the meeting) we have no idea when this occurred. So maybe it is a month later and Tuon has returned to Ebou Dar. Unlikely, but it is possible.