The next day, Merlin decided it would be best if Katie and Kellie got a more extended lesson regarding the Rings of Age, particularly to how it can alter reality. Though Kellie was already plenty experienced with this, Katie still needed to learn the full ramifications.
The two girls were seated on the couch while Merlin was drawing on a chalkboard. Though the blue chalk he was using seemed to shimmer after he was finished with it. Once he was finished drawing a river that had forked many ways, he turned to the girls and said, "Now, you've both heard the concept of time being like a river, right?"
"Sure," said Katie, "Each fork represents a different direction that time could take. The different 'what ifs' that could happen."
"Very good," said Merlin, "Now some changes are radical and others don't particularly matter. Most of the reality changes you two do make a little bend." He drew a small extension onto an existing fork didn't stand out very far from the rest of the main stream. "But a big enough change could cause the creation of a new timestream, which means further changes outside of the ones you were intending." He peered closely at a bulging spot at the head of the river. "For instance, if a certain situation regarding Katie's grandmother isn't resolved soon, it's going to result in a new reality."
"You can just switch back to the original reality, right?" asked Katie.
"Not always," said Merlin, "It's possible to make a change so drastic that it could sever its tie to the rest of the timestream." He demonstrated by erasing a line through one of the rivulets. "And like the branch of a tree, when it's cut off, it will die. The reality after that point would unravel and collapse." The severed rivulet actually withered, turning an ashy brown before it crumbled into nothingness.
Kellie suppressed a shudder. She had done such a terrible change herself, by essentially wishing Katie and Lisa out of existence. Merlin had taken her out of her reality before it became sealed off, but Kellie still felt deep regret.
"Of course, life springs eternal as does time," said Merlin, "When a branch has been cut off, a new one often takes it place." As he spoke, another branch grew out of the stump where the severed one was, but in a different shape. "However, the new reality is without what caused it to sever in the first place and tends to be very different from the others." The new branch was moving further way from the others quite a lot.
Kellie nodded. That was essentially what happened to this timeline after Kellie left. Though she later learned that some of the changes were caused by Morgan Le Fay.
"So anyways, in order for you two to fully learn the implications of reality changing, I asked some guests over to properly explain it," said Merlin. The air rippled and a pair of beautiful blonde women appeared. Katie and Kellie immediately recognized one as the alternate Katie, but the other one they haven't seen before. Well, Kellie had, but only when she aged herself up and looked in the mirror.
"So this is another reality?" asked the adult Kellie, looking around, "Not as different as I was expecting."
"It's usually not the places that are different as the people," said Merlin, indicating the younger Katie and Kellie.
Alternate Kellie gasped and said, "Oh my gosh, Katie. They look just like us when we were 16."
"They are us at 16," said Alternate Katie, "They just didn't grow up together. Also, Lisa is Katie's twin."
"Wow, hard to imagine," said Alternate Kellie.
"So, why are they here?" asked teen Katie.
"You're going to be spending a day with them," said Merlin, "Just something to help you realize the impact of your choices. Have fun." With that, he left the room.
Teen Kellie felt a little awkward. She and Adult Katie were the only ones here who remembered the original timeline, in which she was Katie's mother. She admitted she felt attracted to the adult Katie, but having her own alternate here made things more awkward. She wondered if her Katie was feeling something similar.
"So, what do you girls want to do?" asked Adult Katie, "You want us to become teens again or do you want to grow up. We can work with either or none."
"We can figure out where we want to go after that," said Adult Kellie.