May as well take this opportunity to try a new summary of my theory of "the neverending fight" (the Trant/Forel fight was never ended by GRRM. The fight about what probably happened may last until Martin reveals how the Trant/Forel fight ends).
I'll start with my conclusion, and then indicate the textual support for each premise leading to that conclusion. To save time and space I won't cite actual text unless the support is challenged; much of it has been set forth several times. REMEMBER, please, we're talking about what MIGHT have happened after that last instant, when Arya saw Syrio's stick sheared and ran out the door, terminating our view of the fight. I'll say it here, and I don't want to have to say it again: everything I suggest or conclude about what transpired after Arya left is CONJECTURE. I will state it, however, without constantly repeating that it's conjecture, unless somebody forgets and complains that I'm trying to fool them. Please read the end of the fight scene (p.534 AGOT Bantam PB) if you're not sure what's conjecture and what's canon. Moving on.
Arya fled (canon). My theory for the end of the neverending fight: Syrio convinced Trant that he couldn't be easily killed. Trant, realizing that he had lost Arya and five guardsmen, concluded that fighting further with Forel was a bad idea, especially because every instant he wasted with Forel, Arya was getting farther away. He therefore promptly left to get reinforcements to help him search for Arya before she could get completely away.
Trant is well protected by his armor, so Syrio can't do any significant harm with his stick sword (he's shown hitting Trant with it to no effect). Consequently, Trant is unharmed.
But Trant does what he's told. He doesn't care about honor (for example, he hits Sansa without qualm). He's been told to capture Arya, and Arya is getting away. He might want to kill Syrio out of cruelty, but even if he was capable of doing so (which I doubt), spending time trying to kill Forel would interfere with what he was ordered to do, which was to secure Arya. To comply with his orders he must either run through the kitchen after her, or he must get others looking for her as soon as possible. The fully armored man isn't likely to be successful chasing Arya through the kitchens, especially if Forel is correct that he's "slow, for a knight".
But why didn't Trant kill Forel seconds after Arya left, right after he had sheared Forel's stick? He might have. But the text suggests it's unlikely: Martin has demonstrated Syrio as having a terrific ability to avoid Westerosi swords swung at him. He avoided being hit by every sword swing by all five guardsmen, who attacked him from three directions (canon), and he avoided being hit by the five sword swings we see by Trant (assuming Arya wouldn't fail to think about Forel getting sliced by a sword if that happened). Forel, Barristan Selmy and Jaime have all expressed contempt for Trant, while we have every reason to think that Forel is a superb survivor. Yes, he has only half a sword to parry with now, but the sword wasn't that useful anyway, and other weapons are readily available.
So that's essentially it, I think. Trant left at least because he had no reason to fight, Syrio walked away because he had no reason to pursue Trant. Syrio was not known to Trant (the implication of the ways Trant+5 addressed him), so there is no reason to think he'd be recognized by others; and given his demonstrated skill against the five guardsmen, it's entirely likely that he could leave the Red Keep without being injured.
I happen to think that, far from losing, Forel became a serious threat to Trant, and that Trant probably ran pretty fast to avoid that threat; but that would be icing on the "Syrio probably lives" cake.
Given that Forel, during his fight with the guardsmen, demonstrated a proclivity for knocking opposing fighters off balance and down, and given that Forel chose to engage Trant with only his stick rather than follow the standard wisdom of staying out of reach of Trant's sword, even after finding the stick offensively useless, and finally given that there was little else Forel could do against a fully armored man, I believe he was aiming to knock Trant down. Indeed, he might have been angling to give Trant an opportunity to swipe at the stick, precisely so that Trant would be off balanced when the stick suddenly gave. The stick shearing, then, might have been a sacrifice to get Trant off balance, in which case Trant may have fallen very shortly after Arya left.
Or not; knocking Trant down is just one way Forel could have convinced Trant that continuing the fight was a bad plan. Another way would have been to dance away, after that last cut that sheared his stick, pick up one of the five swords lying around the hall, and use that sword to parry as necessary. Martin shows that Forel is willing to pick up the guardsmens' equipment to protect himself - he did so with one's helmet.
The longer the fight went on, the worse for Trant's goal of capturing Arya, and the greater the danger that Forel might actually hurt him.
In view of the thrashing Forel gave the five guardsmen, it is my expectation that Forel humiliated Trant, causing him to retreat not only to pursue Arya, but also in fear for his life. But though I figure the odds of his having humiliated Trant (for example, putting him on the floor like a turtle) are pretty good, say 50%, the odds of his surviving the fight are much higher. It requires only that he want to live, so if he is unable to knock Trant down or harm him through his armor he will do something else, such as keep his distance and use his speed and much better mobility to stay alive. Dancing, but not running, is necessary only in the worst case.
Here's why I think Trant couldn't hurt Syrio, assuming only that Syrio wanted to stay alive: Syrio had survived fights for many years, and knew exactly the risks involved. He had other options than engaging Trant to accomplish his goal of letting Arya get away, such as some sort of dancing about the cluttered room to use his mobility advantage over Trant. He didn't choose the safer, more conservative alternative of keeping his distance; so if he loved life, it's reasonable to expect he thought the risk of engaging Trant was pretty low, especially in view of his stated contempt for him. Given his ability to avoid the blades of all five guardsmen, I'd say he knew very well what he was doing. (paragraph edited for clarity)
Thus, I think it is extremely likely that Syrio Forel survived his (brief) fight with Meryn Trant. I also think it is somewhat more likely than not that he will be reintroduced, perhaps reuniting with Arya - the Braavos nexus is pretty clear. I admit that the likelihood of his being reintroduced has dwindled with the expansion of the series, which has caused there to be at least three complete books between the book in which he disappeared and the book he would be likely to return in; it may begin to seem cheesy to Martin to bring him back after such a long hiatus, so even though (IMO) he probably originally intended such a reconnection, he may now have written him out of the story.
Here are two reasons I think Martin originally planned to bring Syrio back: first, the fight scene is loaded with "cliffhangeriness", features that make a popular character seem in jeopardy of death. Such scenes often result in the character surviving, and that is an especially likely case here, because those textual clues that are less showy than the sheared stick strongly suggest (to me, I know some disagree) that Forel should easily have survived. Thus, though I put the probability of his surviving the fight with Trant at 90% (yup, I've raised it), I can only put the probability of his return at about 51%.
Edited by AvengingAryaFan, 17 December 2010 - 09:37 AM.