In the past, before Mickey ever met Minnie, he was Yen Sid's only apprentice. He wasn't receiving any lessons at the moment, stuck doing chores. According to Yen Sid, it was to teach him responsibly and to tone down his mischievous tendencies, seeing as being a keyblade master required someone with discipline. Though Mickey was convinced it was just so he'd have an excuse to give him all the tower chores.

After dumping his two pails of water into the basin, Mickey peeked in to see Yen Sid summon a gargoyle-like creature of the smoke from a crystal skull. It suddenly swelled up before bursting into a butterfly of many hues. The demon into a creature of good.

Mickey watched in awe as he leaned against the doorframe. He wished he could use magic to the extent his master could, he didn't even need his keyblade to use it.

Yen Sid suddenly made all the colors slip back into the crystal skull, sealing it away. He then gave a yawn, exhausted from purifying dark creatures all day long. He carefully took off his star-covered hat, placing it on his desk before heading off to bed.

Seeing the hat glowing so brightly filled Mickey with hope. It still had some of Yen Sid's magic inside! This could be his only chance to see what it was like to be a great wizard!

He tip-toed over to the stairwell to check Yen Sid was out of sight before racing over to the hat.

With a flourish, he placed it on his head.

Riku awoke to find himself seemingly back in Yen Sid's tower. "The test can't be over already, Kairi and Sora haven't woken up all the worlds yet, it's supposed to be seven in total."

He looked down to check he was still in the uniform the Dream had provided him, proving his theory.

He then heard a mumbling and turned to see a young mouse fast asleep, Yen Sid's hat nearly slipping off his head as he seemed to conduct some invisible score. Riku recognized him as yet another young version of the king.

He looks like he's trapped in some sort of nightmare… Probably due to the darkness I'm sensing… Riku thought before pinpointing where it was coming from: a music stand behind the mouse.

He walked up before summoning his keyblade and charging up his light.

Oh, I don't know if your light will be strong enough to defeat this darkness…!

"Sounds about right, it never is." Riku sighed in disappointment in himself before realizing it wasn't his doubts manifesting themselves again, it was Mickey.

He turned to the mouse to find him still fast asleep.

"My name's Mickey." He introduced himself, startling Riku. The voice was simply in the room, he had no idea where it was coming from. "I'm the sorcerer's apprentice. Who are you?"

"Um, I'm Riku." Riku responded. It felt strange reintroducing himself to someone he'd only met a little while ago. "You need some help dispelling the darkness?"

"Oh, yes! I would try myself but I'm trapped like this!" Mickey sighed in relief. "Thanks Riku, you're a real pal!"

"No problem." Riku smiled faintly. "So what do I need to do?"

"You need to find a Sound Idea." Mickey explained. "It should have enough power to dispel the darkness. You'll find one in here."

Another musical stand suddenly appeared before Riku. The score was titled Symphony No. 5.

He summoned his keyblade and pointed it to the stand. After his keyblade let off a beam of light, a symphony filled his ears as he was sucked into the music.

Riku found himself standing on a comfortable cloud as music began to play. He looked up to see a beam jumping from cloud to cloud, letting off bright splashes of light as it did. It dove into the lake below.

Just as Riku was wondering if the light had been extinguished, a flurry of colors burst out of the water, taking flight. He realized quickly that they were butterflies made of folded paper. Only two remained at the surface of the lake, an orange butterfly and its child.

"Let's go check it out, Kou." Riku suggested. "They might know where the Sound Idea is."

Koumori nodded before fusing with him.

Riku fluttered down to the lake and was surprised to find he could walk on the water, each step making a new note and ripple of light.

He walked up to the little butterflies who were happily splashing each other. "Um, excuse me-"

But before he could ask them anything, the ground suddenly cracked beneath them as the music grew faster. Darkness surrounded the three as the cracks began to glow.

"Time to fly!" Riku called, usher them away to avoid a burst of fire that came from the cracks.

They wove through the shoots of fire as the ground suddenly exploded, releasing thousands of black and red Nightmares shaped like butterflies.

"Go join your friends, I've got this!" Riku assured the pair. They fluttered off to find the rest of their swarm, the colorful mass far ahead of them.

Riku summoned his keyblade, trying his best to fight off the creatures. Each hit made a note in time with the music.

The Nightmares suddenly merged together, creating a giant beast that towered over Riku.

The boy fought the winds produced from the beats of its wings but was soon flung onto his back.

He looked over to see the pair of butterflies being cornered. The mother flapped her wings, trying to protect her baby before it's wing was slashed through. With the last of its strength, it pushed its child away. The white butterfly looked around worriedly for an escape.

"Don't touch her!" Riku yelled at the beast. He then shoved himself forward, kicking the monster with all he had.

It dispersed at the powerful blow, now defeated but their destruction caused the world to be engulfed in darkness.

Before him floated a single sheet of music, glowing brightly. A Sound Idea.

Just as Riku took it, he heard a clap and turned to see the young man from before. The little butterfly fluttered wildly, trapped in an orb of darkness.

"Let her go!" Riku yelled in anger, summoning his keyblade.

"Poor little thing, so tiny and fragile." The man said with a chuckle, watching the creature's light fade as her flaps became weaker. The orb tightened around her. "The more its light burns, the deeper it will descend into the darkness, never to be seen again. Just like your precious Sora and Kairi."

"What?" Riku felt his heart ache in fear. He'd said something like that the last time they met…

"Soon you'll understand and once you do…"

Riku felt his head begin to spin, his body growing heavy. He weakly reached for the butterfly, his fingers grazing its cage before he collapsed.

Riku… Riku!

The boy slowly awoke to find himself back in the tower. He looked up to see Mickey still asleep at the desk.

Did the music give you a bad dream too?

"A bad dream… yeah." Riku whispered. That's all it was, a bad dream. He thought to himself.

He walked up to the music stand to see the Sound Idea glowing brightly in front of it.

Thanks for finding the Sound Idea. Mickey said. Want to try it out?

Riku nodded, summoning his keyblade to conduct.

The Sound Idea turned into light, making a beautiful but incomplete sound. It flew into the music stand but the darkness didn't fade.

"It wasn't enough…" Riku sighed in realization. Maybe this was foretelling what was to come. "I couldn't do it, I couldn't save you…"

Just then, two other musical sheets appeared before turning to light and joining the idea. Together, the three made a warm and wonderful song that could melt any heart. The darkness disappeared.

Mickey awoke, giving a yawn before getting out of his chair. He smiled at the music before looking at Riku. "Looks like you just needed some help! And that's alright, you can't expect to do everything on your own."

Riku smiled sadly. "I guess I kinda got used to that. I was always the one doing all the work between my friends… and then they weren't even there for a long time… Guess I better get used to depending on them, even if I don't like it."

Mickey noticed his sadness. "What's wrong, Riku?"

"I just wish they could do the same..."

That would only happen if he got stronger and he wasn't trapped in this dream, no, this nightmare.

The seven keyholes were unlocked. It was time for the sleep to end, wasn't it?