The Inbetween

"Don't stray from the path."

The Inbetween is a separate dimension that can only be accessed through DreamXD's World. First seen in The Masquerade, it is one of two worlds that Karl can travel to - the other being the Other Side.

History
A full transcript of all books found in The Inbetween can be found here.

The Masquerade
After Karl was killed during the events of The Masquerade, he appeared in the Inbetween. He found a book explaining that the Inbetween was a gateway for traveling in time and that it served as his "home away from home." It also told him that, exploring the castle, he would find out more about his time-traveling abilities.

Karl wandered around the castle, and found a white tree with a swing set in front, bearing a strong resemblance to the Tree Dome from Mizu. A second book on the trunk told him that, while Karl's time-traveling would remain an involuntary thing, he will be able to find a way to mitigate the damage it did to his body and mind.

Karl left the tree and climbed a flight of stairs until he wound up at the top of one of the towers. A third book told him that he needed to continue time traveling to document the events of the server's past and future, and that preservation of these stories was the most important thing.

Karl looked at the rest of the Inbetween from one of the windows and was then transported back to a cave leading back to his library through unknown means.

The Wild West
After Karl was transported back to the Inbetween after his visit to The Wild West, he found a book that told him to explore more of the castle. He did so, and discovered that there were many versions of himself roaming the Courtyard, but they did not respond to him and seemed able to walk right through him. He continued onwards and found a book that told him the castle was alive and sentient, and that this would help him find out how to keep retaining his memories.

He found more books, one of which told him to check under the tree. The book underneath the tree had 87 pages, the first of which only contained the phrase "DONT STRAY FROM THE PATH" repeated across the entire page. The final book he found told him that he would one day find a way to stop losing himself and his memories. He was transported away from the Inbetween, presumably back to his library.

The Haunted Mansion
After the events of The Haunted Mansion, Karl seemingly traveled back to the Inbetween. When he got there, he started exploring new rooms of the Inbetween, which had books that mentioned the portal inside of the Inbetween, a place Karl hadn't been. The books told him somebody was watching, and referred to the unknown entity as "it." He found several books which kept on telling him to not "STRAY FROM THE PATH", similarly to his last visit. He then traveled back to his library, and wrote about what had happened.

The Pit
Karl traveled back to the Inbetween after the events of The Pit, and started glitching from the normal Inbetween to a somewhat darker version of it. Both sides had books which heavily contradicted each other, but they seemingly kept talking about the portal. He eventually gave in to the side that told him to go into the portal, and went inside of it.

The Main Room
The main room of the Inbetween is a massive, white hallway made out of - among other things - white stained glass, quartz, light blue terracotta, diorite, and white concrete. In the center of the hallway is a small pedestal with a single, potted wither rose. At one end is a doorway leading out into a courtyard, at the other is a staircase leading up to the entrance to the rest of the Inbetween.

The Courtyard
A courtyard with a large, white tree in the middle and a swing set in front. The tree is made of birch logs, white glass, and end rods, each of the corners has a planter with some lilacs and blue orchids while the rest of the courtyard has the same motif as the entrance. The tree appears to be modeled after the Tree Dome from the Lost City of Mizu, as the general shape is the same, and the swing set is identical to the one in the Tree Dome.

The Garden
A garden inside the walls around the outside of the castle. It is largely comprised of a lawn, and there is a small platform with flowers on top of it on one of the lawns. There are birch trees dotted long the lawn. There is a staircase leading down to the garden past the Pool.

The Pool
A swimming pool with lily pads on the water. It is located on the way to a staircase to the Garden.

Front courtyard
A courtyard in the very front of the castle, containing a fountain and two staircases up to a large white tree. In Tales From the SMP: The Haunted Mansion Karl finds a hidden room under the large white tree.

Portal Room
There is a small room containing a nether portal near the front of the castle. It is visible from the outside by a large window. The entrance to the room is blocked by iron bars.

Trivia

 * The Inbetween strongly resembles the White Room in the Old Mansion from Kingdom Hearts II, which in and of itself is a reference to Castle Oblivion (from Kingdom Hearts: Chain of Memories).