Mind sharing those ones, too?
Sure.
AFFC really killed the idea, for me. Jaime's conversation with Longwaters (the jailer) makes it clear that there were only three men in the Black Cells when Yoren arrived, and that Longwaters knew who they were. So Syrio cannot have taken Jaqen's place: that would mean four men were in the cells, including Syrio.
Possibly Jaqen was never there, of course, and one of the three Longwaters refers to is Syrio. However, this doesn't really fit how Longwaters speaks of the men. Nor does it explain why Syrio would take the risk of changing his identity while in the cells. For one man to go in and another (who was never officially there) to come out is going to cause comment. We know that those going in are recorded: it is not unreasonable to think that those going out must be, too. Certainly it's a risk big enough to make the switch inexplicable.
(Longwaters' conversation also backs up the timeline argument: he doesn't specifically say when Yoren came to the Black Cells, but there's a strong indication that it was when Ned was still in power.)
Notwithstanding the comments above from The Imp, it is also very unlikely indeed that Syrio was not killed fighting Trant. The author takes pains to indicate to us that this was the case, and realistically Syrio's skill is not going to overcome Trant's superior armour. (In fact, there is a strong argument that Syrio not dying at this point would cheapen the whole scene and be bad writing, but that's another whole debate.)
For Trant to capture rather than kill Syrio is inexplicable, too. Trant was trying to capture Arya: that was his mission. And she had fled. He would not have stopped to detain Syrio, rather than pursue her. He had no reason to. And even if Syrio had been captured, why was he not executed? Every other Stark retainer we know of was killed, after all, down to Septa Mordane. Why spare one who had killed several Lannister guards?
And if for some unknown reason he was captured, why did Cersei show no interest in him thereafter, even though she was desperate to find Arya?
Either Syrio died in the fight, then, or he escaped. If the latter, how did he wind up in the Black Cells? And why, again, did Cersei and Trant apparently forget about him, or not care about his escape?
Basically, for Syrio to be Jaqen, Trant has to have taken him prisoner when it would be easier to kill him, he has to be the only Stark retainer not executed, Trant and Cersei have to then forget about him, he has to change his identity for unexplained reasons, and a man of the Night's Watch has to be allowed to empty the Black Cells on the strength of an order from the deposed Hand who is sitting next door, at a time when the Red Keep is sealed.
I could add that Syrio and Jaqen have completely different personalities as well as appearances and that there is actually no positive evidence to suggest that the two men are the same person, but at this point it feels like kicking someone who's already unconscious.
The Westeros forum is the one I never read because the color scheme is atrocious and hard on my eyes. The main site is also unnecessarily hard to navigate. They should take a lesson from Tower of the Hand. Anyway, that's why I missed out on the timeline discussion!
As Wert says, we have three colour schemes, but the two alternates (black background (Targaryen) or grey background (Stark)) are only available if you register.
