He discusses this with Cadence

Spike chose to stay with Cadence, for now at least. If only since he really desperately wanted some pony to help him sort himself through this mess. And well Cadence was probably one of the few who wouldn’t judge him for what had happened, or more importantly Rarity.

“I have to admit Cadence I need help. I’ve well- I’ve really screwed up there was this root and magic and Rarity and-“ Spike babbled but calmed down when Cadence placed her hands on his shoulder.

"Calm down there Spike, you sound like Twilight. Just take a deep breath there,” she firmly ordered. With immense difficulty he took three deep breathes. The first one was painful and difficult as his every muscle seemed to strain against him. But each one got easier and easier.

“There, you okay now Spike?” Cadence asked her voice naturally soothing. Spike nodded gently, but he was still too terrified to speak. "Why don't we sit down in the park?"

Cadence led the two of them into the park, and was quick to find a bench by the pond. Spike was fidgeting with his fingers, avoiding eye contact. Trying to think what he was going to say, how to make sure he didn't accidently use a yes or no question.

'Then again didn't Rarity say that she wanted Cadence to be a part of that harem in her fantasy?'

Spike's blood froze at the foreign thought in his mind, and he immediately became worried for Cadence’s sake. But found his feet unable to move, he guessed it was either the spell or his nerves.

"What's wrong Spike? You're clearly anxious about something,” Cadence said, noticing his jumpiness. “Take another deep breath.”

Spike did so, calming down significantly.

“Feeling better?”

“A bit,” he admitted but his voice was hoarse with worry.

“Ready to talk about it?"

"Okay,” Spike said, taking one final deep breath. "I was exploring the Everfree Forest earlier, looking for gems for Rarity when I came across this cave. It was made out of crystal just like the Tree of Harmony."

“The Tree of Harmony?” Cadence exclaimed in surprise. “Was it some kind of secret entrance?"

Spike shook his head. "It wasn't actually, it apparently led to what was called the 'Root of Honesty'. There was a magic flowing through there that affected me."

Cadence had been listening patiently but at this she became concerned. "This magic isn’t dangerous is it? We’re not having another inspiration manifestation incident again."

Spike scratched the back of his head. "It might be similar."

Cadence frowned. "Spike haven't you learned your lesson by now?"

"Hey I didn't touch anything this time. I was just exploring and by the time I noticed any magic I was already affected." He protested, defensively waving his hands in front of him.

Cadence sighed. "So what kind of magic are we talking about here?"

"Basically if I ask any yes or no question the answer is automatically yes," Spike explained. "Even if reality has to change to make it true."

To his disappointment Cadence seemed skeptical of this claim. "That seems like quite the magic, but not one I've heard of before. Nor Celestia or Luna I think."

"You don't believe me."

"Sorry Spike it's just hard to believe. Perhaps a demonstration?" She suggested causing Spike to hesitate. The Root of Honesty said that no pony would notice the change unless he asked a question to make it so.

“You won’t notice unless I ask you to. So will you be okay with any changes I make?” Spike said before slamming his hands over his mouth. That wasn’t what he meant to say. It seemed the spell had a way of warping his questions so that they came out to benefit Rarity’s perverted dream.

‘Or maybe I just misspoke? I do tend to do that when I’m nervous.’

That actually was possible. Cadence however seemed to smile. “Don’t worry Spike you could turn the sky green and I wouldn’t mind.”

Well in any case he would have to see again. “Will you notice any changes I make with my questions?”

See nothing to worry about. Maybe he did just let nerves get the best of him. Twilight must be rubbing off on him.

“Yes I think would if you changed the sky green,” Cadence answered, she seemed confused. “Are you stalling Spike?”

“No I’m just trying to make sure you notice it. Normally ponies don’t notice when I change things." He explained before scratching the back of his head. "Um... what should I change?"

Cadence paused for a second, trying to consider exactly what he should change. "How about something impossible but not too drastic? Like perhaps what if I was wearing a different outfit?"

"Yeah that could work. Cadence are you wearing a T-Shirt and shorts?

Cadence’s eyes widened in surprise as her outfit changed before her eyes. Becoming an incredibly tight T-Shirt and tiny booty shorts, both were too small for her. Squeezing her skin, and tracing her **** figure, so much so that it sent Spike into a blushing mess as he broke eye contact.

“W-wow you’re really not kidding,” Cadence admitted astounded. Her eyes noticed that no other ponies paid any attention. "And we're the only ones who noticed..."

Cadence appeared stunned, and was still trying to process this information. "So Spike you're worried about making a mistake with this power right?"

"Yeah that's about right."

"Well there's obviously a lot of potential to **** that power, but there's also a lot of good you can do as well." Cadence assured him but that's where Spike's face fell.

"That's where I became the most anxious actually, since I did try that. But I asked Rarity whether I would always help fulfil her dreams and well they were a bit more… explicit than I thought." Spike admitted, fingers fumbling in a panic. "You can't tell anypony."

"Not a word Spike," Cadence assured him, and to which he began to explain the full details of Rarity's fetish. Trying to sugarcoat it wherever possible but nevertheless unable to make it sound okay. When he was done Cadence's cheeks were red. "That's... I mean wow. And she included her friends, her sister and the Princesses including me?"

Spike could tell Cadence was concerned with this, even if she tried not to judge Rarity. "And now because of what I said I'm going to be **** to fulfil that fantasy and with my power who knows what I'll do to you and the others."

"It's okay Spike," Cadence tried to assured him, but Spike waved her off.

"No it's not. Rarity's fantasy is going to turn my friends into sex slaves using this power, including you. Do you want Rarity's fantasy to come true? I'm not going to be able to stop myself. I'll have to run away before I can hurt anypony through my stupidity. No pony or dragon should have this power. Would you manipulate this power like that? Of course not so I shouldn't either. I can't stay here before I run my stupid mouth and do something terrible." Spike ranted to himself, wringing his hands in a panic. He was oblivious to the subtle change in Cadence's demeanour, unaware that he already had.

A/N: Following requests I've tried to make sure this chapter was longer. It was a little difficult to write as Spike is still at the stage where he's still not going to turn Cadence into an enabler, but I got there now.