The goggles were the most intimidating bit, Shining had worked out. "Why does there need to be straps?" The stallion flexed against the restraints, finding that short of magic he wouldn't be getting out of this until his sister was done with him.
"Oh? Those are to protect the machine, if you move it would mean I need to recalibrate and that takes far too long." Twilight floated her scroll over, ticking off 'bind subject down tight' off the list. "Now, Spike! Throw the switch!"
The little dragon saluted, standing on a stool so he could reach the lever on the side of the huge contraption that looked to be aimed at Shining Armor's head. "Right away, Twilight!" He had to jump the last little bit, to grab hold of the knife-switch, using all his strength and bracing his feet on each side of it to pull it down.
Electricity arced across the contacts on the switch as the dragon turned the contraption on. Shining looked up to see spiraling arcs of electricity racing around the huge, glass-ringed and tapering conductor.
The reflection off of Twilight's goggles gave the mare the look of the maddest of mad scientists. She adjusted a dial on the side of the machine with her magic, heralding a rising whine coming from the cabinet.
Shining wanted to close his eyes but didn't dare look away as the brilliant white-blue flash of power had him seeing stars and black dots. "Twily?"
"Success!" Twilight lifted a hoof in victory. "Spike, turn it off!"
Spike spat into his palms, this was the bit he always had trouble with. More flashes started going off, strobing right before Shining's vision and leaving the poor stallion dazed.
Twilight dashed over and reached up with her magic, shutting down the machine herself and saving her brother from what would have been the worst headache in the history of forever. Although, as it was, his vision was filled with black and purple blotches, the one that started talking to him, he assumed, was Twilight.
"We did it, BBBFF!" Twilight dashed back to her machine, watching as it disgorged a picture that showed a perfect outline of a pony head, with all kinds of squishy bits inside it. "Oh wow, look at this!"
She held the picture up to Shining Armor's nose. "Look, there are changes in this squiggly bit, and your horn is starting to change, right down here, see?" Twilight had neglected to untie her brother, not to mention offer him some eye drops so he might one day see again.
"Twilight Sparkle, what have you done to my Shiny?" Cadance stepped in, her magic reaching for the restraints and undoing them, only to have a picture shoved suddenly in her face.
"But look, he is changing more, inside!" Twilight stared up at Cadance, the goggles hiding the manic stare she had.
"Cady?" Shining managed to squirm free of the last of the bindings and realized he couldn't see but, somehow, knew he was looking right at his wife. A silly-happy smile covered his lips. "I survived?"
Cadance wrapped her husband in a soft wing, hugging him. She felt the slight, butterfly-feet feel of changeling feeding, but it was coming from close. Cadance got a hint that it was her husband and focused on him, pouring her love of, her desire for, and her complete devotion to Shining Armor into feeling.
Blinking, Shining felt like he was staring at the sun. The surrounding wing burned with heat, a heat his body wanted, needed. "Cady? What… what is happening? Are you okay?"
"Shh dear, just relax. Your sister seems to have helped trigger a new change. You can feel the warmth?" Cadance felt her dear husband nod against her side, his eyes furiously blinking away at the blotches of color. "Then you can feed, like a changeling. Maybe that will mean you can shape-shift soon?"
"If my hypothesis is correct, then if the subject is feeding and stocking up changeling energy, it should be able to shape-shift shortly, yes." Twilight had her notes out and was reading from them. "Err, he… my brother…" It was hard to marry her love of science with her love for her present subject in his normal disguise as her brother.
A hoof lifted up, a big white one, with little holes in it. It wrapped around the lab-coated pony's withers and pulled her into the hug. "Twily, never change." Shining had felt his sister by that new feeling, it was amazing. But the most amazing part was Cadance.
Shining rubbed his leg again. "So I should picture it, just like how I want to look?" He was trying to focus on the words of Careful Steps.
"Yes, build the image, put into it only what you want to look like, your nature will take care of the other bits. Now you have that picture in your mind?" The drone was patient, taking time out of his day to help his new queen's mate was not the most fun thing, but it certainly beat the 'honors' his old queen gave out.
The image Shining built in his mind was of himself. Strong, with whole legs, no slightly dark horn and certainly no fangs. He knew the image so well since it was him only a scant few months ago.
"Now, bring up all that energy inside, that you felt when our queen feeds us. Let it flow over you, let it free." Careful drew his own power out, demonstrating. As the flames started to pour from his hooves up, he felt a call within the stallion. Victory.
Shining's eyes flew open, he watched as the fire poured past them and felt the searing, delightful heat of his change. Gone were the holes, gone was the odd horn color. Opening his mouth he found only flat, normal pony teeth. He jumped into the air and clicked his hooves together before diving on the changeling and hugging what he hadn't realized was a perfect copy of his own wife.
"Why, Shining, what will Cadance do if she catches us like this?" Careful booped Shining on the nose, as he had caught his queen do to the stallion.
"I think I would congratulate a good teacher and a wonderful student. Come here, my Shiny." Cadance's command was undermined as she dashed to her husband, as eager as Shining was to hug. "I knew you could do it."
Shining pressed in tight to Cadance, feeling a wing pull around him, then another. "I… I really am a changeling now, aren't I?"
"Of course you are, silly. You are the cutest changeling in all Equestria, clever too." Cadance kissed her special somepony.
Poor Careful never made it to the door. Other changelings, for the rest of the day, would tell cautionary tales about being in the same room with the queen, when she and her husband were close. The drone was flopped on his side, gazing with glazed-over eyes at the pair. His mouth worked but no sound came out. Bliss claimed him in its tight embrace.