It has been a while, so here's some background info.
Most people who travel between the arcana are keys. That means they have the ability to "unlock" the Royal Road and use it to travel between arcana. This is explained here
. There are some limitations, of course. First, you can't travel directly from one arcana to another. You get from the Moon to the Three of Cups, for example, you have to first travel from the Moon to the Fool and then from the Fool to the Three of Cups. The Fool is always a destination point. Second, the Royal Road only connects to one specific location in each arcana. You have to be in that location to activate the Road.
Keys may bring others with them through the Royal Road.
Chrys and her father, on the other hand, are not keys. They are members of a long lost, semi-mythical race called the Dreamers. They are first mentioned here.
As Dreamers, Chrys and her dad have the ability to dreamwalk. That means they can travel from arcana to arcana directly, without using the Royal Road. There'll be a more indepth explanation on how that works towards the end of this chapter. However, Chrys has already dreamwalked more than once
Dreamers can also bring others with them when they dreamwalk, though the sensation is unsettling (and explains why Theresa passed out the first time she experienced it).
I hope this helps clear things up. I know with a long term webcomic that doesn't update every day, it can be hard to follow continuity. Things are very spread out.
Any other questions?