Tails knew he couldn't trust Rouge to not try something like this again, despite her possible pleas should he try any other device. She would definitely look for a way to squirm out of any kind of punishment for her stealing tendencies, or worse, she would try to use his inventions against him. In truth, Tails has many inventions he doesn’t share with his friends, less with the public. All of them should work, hypothetically, but he hasn’t run tests on them enough. Rogue here could be a very good candidate to test them all, but if she somehow gets the upper hand she will make him wish he just gave her the emerald when she first appeared. Tail was aware of this, his mind already imagined the possible scenarios. This was the one where he would always be safe from her, and would also stop her from causing mischief. A possession machine. Initially it wasn’t that, it was more of a permeability device that would make a material easy to slip through, basically allowing one to go through walls or solids. It would have been a huge boon for Sonic for sure, but the device didn’t work as intended.
Rather than allowing him to slip past inanimate matter, it allowed him to slip into organic matter.
Tails knew he couldn’t give the device, which looked like gloves, to Sonic. It allowed the user to slip into organic matter, not through it. Which meant that Sonic would just have some very awkward moments whenever he tried them while running. He had tested them a few times with things like plants or some of the smaller animals that roamed around. It wasn’t seamless, Tails had to put extra effort to fit his frame into whatever he tried it on, but once inside it was like wearing a suit. He could move freely after fitting his whole self in, and could also perceive what appeared to be memories of what he tested it on. But anyways, he never tested it on another inhabitant of Mobius aside from the small animals. This however, was the perfect opportunity to use it. Tails may be somewhat young still, but he’s already starting to experience attraction to the opposite sex. And Rouge’s body was… perfect. At least in his eyes it was. If he was the one behind those eyes, moving those hands, speaking through that mouth… he felt his heart beat fast as he prepared himself. Rouge was tied up tight, and couldn’t stop him even if she tried. So with one last deep breath Tails put on the gloves and approached Rouge.
The bat could hear the steps echoing as she tried to free herself from these ropes, but no matter how hard she tried they just didn’t give way. If anything, it looked like they tightened themselves more somehow. Then, she felt a cool sensation on her back, Tails’ hands moving around it. “What’s this? Here to give me a massage~?” Tails didn’t respond to which she huffed, until she felt it. His hands… sinking into her. She could only gasp as she felt something grab her from within and… open her up. “T-tails!? What are you doing!?” She screamed at him as she felt something in her leg, sliding into it. And then, she couldn’t move it anymore. Her blood turned cold at what she guessed was happening. “Tails!! You don’t need to do this!! I-I can… just leave the emerald alone and go somewhere else! I won’t bother you again!!” Her pleas fell on deaf ears though as she felt another leg slide into her own, losing control of both of them. “Aahhn~!” She let out an involuntary moan as she felt the young fox assess himself over her body. She was starting to feel pleasure, trying her hardest not to moan and to move, but her strength was leaving her. Both in body, and mind. Soon she felt herself stand up as Tails started pushing his hands deeper. “Oooooohhhhhhh~” By that point all resistance was lost, the sensation was too strong. Too… pleasurable. She… she wanted more. She wanted Tails inside of her right now. She wanted him to take the reins, to take her body, to take her life. “G-get in… quickly, take me… Tails~…” She said drowsily, eyes foggy as she kept moaning. Tails was almost there, he could feel his lower member hardening through the process but he tried his best to ignore it and get this done. It was the last push. He just needed to… push his arms deeper and…!
“AAAAAAAAaaaaaahhhhh~...!!!” Rouge moaned loudly, an orgasm like no other striking her whole frame. Her eyes rolled into her head as she fell unconscious.
When Tails next opened his eyes, things felt… different. He had blacked out for a second, and felt sort of lightheaded. “Did it work?” He asked himself only for his eyes to widen at the sound that came out of his mouth. It wasn’t the voice of Tails the Fox. No… it was the voice of Rouge the Bat. He looked down and felt his face heat up when he saw a pair of big, round firm breasts on his chest. He tried to move his hands but saw he was tied. “Oh, right.” He felt weird speaking with Rouge’s voice, but he tried to power on. “Code 632145.” He said with Rouge’s voice and the rope came undone, only to reveal itself as a group of small machines that just kept the appearance of the rope. Tails moved his new arms, testing them and flexing his new fingers. He was able to feel everything, the feeling of Rouge’s clothes on his arms, the wings on his back, the sensation of lacking something in his nether region and that of her big breasts on his, or rather… her chest.
Tails smiled. “Alright, I’d say this test was a success!” She raised one arm in the air to celebrate as she started stretching, feeling every muscle on her new body. “Now… what to do?”