It isn't time travel really. It's more like a magical portal back to the other side of the bridge. The group goes through the bridge, wary and silent, and the stonemen take no notice of them. And then young Aegon confronts Tyrion about what Tyrion knows about his identity and Tyrion starts mouthing off about his own identity and Aegon's identity -- Rhaeger's son -- and Connington's and suddenly, they are back where they started before the bridge, facing the hazard again: "No, thought Tyrion, that is not possible." -- magic is happening. "We've left the bridge behind. Rivers only run one way." "Mother Rhoyne runs how she will." -- Weird, magical things and dangers occur on this river, especially in the areas of the magically destroyed city ruins. This has already been established repeatedly in this part of the story in what they tell Tyrion on the river journey, deliberately. That part of the river is like a haunted Bermuda Triangle. It's not a current, it's not a circle. They didn't get lost in the fog and somehow are able to go upstream against the current without noticing it or going backwards under the Bridge of Dream without noticing it. There are no tributaries that they drifted into. They had to go past the broken bridge and the somewhat dangerous stonemen as there is no way around it. They were downriver and suddenly they are upriver of the bridge again. It's magic. And this time, the stonemen don't ignore them, despite fog and moss. This time, the stonemen very deliberately attack them. The first two are knocked off before having time to do much. The third one has a shattered leg, but even with it he "lurched forward, reaching for Young Griff...as he tried to close his fingers to grasp. The boy stood staring..." The object of the attack is the prince. Tyrion goes to the rescue, knocking Aegon over and slashing at the stoneman with a torch, driving it back. The stoneman knocks the torch away. And then one of the other people shouts: "The prince! Protect the boy!" and then the stoneman charges again, which causes Tyrion to send them both into the water. Magical forces want the prince. If Tyrion had kept his mouth shut, they'd have just kept going downriver. Val and Jon talk about the princess and grey scale: Val tells Jon that they kill children with grey scale, that wood witches north of the Wall know that it's dangerous and will come back, that the princess is actually a walking dead person, that she is not clean. That refers to disease but also to the zombie wights -- the walking dead and lurking magic. Martin has that conversation deliberately to show that the princess is not simply a sufferer of a disease. Otherwise, why have it? Why have the princess character with grey scale at all? Why would Jon worry about it when Val is so insistent and "this was a Val that Jon had never seen before"? Martin sets it up, connecting with the stonemen on the bridge, the stonemen who attacked others, like the wights do -- those with grey scale are not safe, are dangerous and not simply as raving madmen. This is what Martin does with his ravens and wolves and trees and the legends and stories that some characters tell with great seriousness and others poo-poo. Jon has learned to listen to the wildings but this time, he doesn't really want to listen. Which never turns out well for Martin characters. Anyway, what the stonemen/grey scale will turn out to be and the connections with the wights are not all spelled out yet, but Martin shows that the disease is connected to things. Otherwise, he could have just given them boils. And Tyrion and his group are deliberately and magically targeted on the river to get at Aegon.