Merlin would have been involved with the battle himself. But the battles between himself and Morgan LeFay tended to be very catastrophic on their surroundings. Whole cities have been leveled by their fights. And Morgan had a more adaptive mind than Merlin and already knew his tricks, so a stalemate would have been the best outcome. However, Morgan was dealing with several woman she didn't know as well as she thought and they had a stronger bond than she could break.
When Merlin arrived at the college campus, things had been pretty wrecked by the fight. It was going to take hours to restore the battle-scarred campus and probably longer to alter the memories of the non-magical witnesses. But by the looks of it, everyone made it out okay. Passing by the various couples, he headed straight for where Morgan LeFay was. He found her asleep, swaddled in the remains of her cloak, and held by Katie. It was hard for even Merlin to believe that the most powerful and evilest sorceress of all time was now reduced to a newborn babe.
"Well, of all the possible defeats of Morgan LeFay, I think is probably the most unlikely," said Merlin.
"It took all of our efforts to do it," said Katie.
"Can you believe this what she looked like over a thousand years ago?" asked Kellie.
"Well, the Morgan I knew back then had raven hair and her ears were pointed," said Merlin, rubbing Morgan's tiny head to feel the blonde wisps and her round ears.
"Pointed?" asked Kellie.
"Well, she was half-fairy. That's what 'LeFay' means," said Merlin.
"Is she still half-fairy?" asked Katie.
"No, she appears to be completely human. It wasn't just the Rings of Age that reset her, it was the Rings of Transformation. As I recall, she was using Katie's form earlier, maybe modifying it. The Rings of Transformation made this her default form," said Merlin.
"So she really is my daughter?" asked Katie.
"If you want to be technical-" started Merlin.
"Doesn't matter. We're keeping her," said Katie.
"I hope you realize what you're getting into," said Merlin, "She may no longer be LeFay, but she'll still grow up to be a powerful sorceress."
"So will Lynne, but we're not going to let her go evil either," said Kellie, "How did Morgan go bad?"
"It was...a darker, more intolerant time," said Merlin, "Alliances of power meant more than family ties. Women had no real independence or power themselves. And being half-fae made Morgan a natural outcast. It was easy for a girl like her to go dark in such a time. With you two, I hope she'll do better."
"It really is over, right?" asked Kellie, "Morgan's defeated for good and no one coming to avenge her?"
"So long as you never reveal her past life, until she's old enough to accept it and not be tainted by it. But otherwise, the threat is gone. Mordred has been dead for centuries and Morgan's fairy family is unlikely to take vengeance, if they're even still here," said Merlin.
"In that case, she's Morgan Carlson from now on," said Katie as she rocked her new daughter, "But if I'm going to be her mother, I better fit the role better." She put a hand to her chest and breasts became larger, filling up with milk.
"Now the wedding dress will need to be refitted," sighed Kellie.
"You could do the feeding yourself," said Katie, pointing a finger.
Kellie looked down as her breasts swelled out. "Very funny," she said, changing her breasts back, "But I'm not getting my dress refitted."
"Well, you two seem to have things well in hand," said Merlin before looking at his pocket watch, "My alternate self should be along soon to take our visitors back. I'm sure this will be just as much a surprise for him."