Fix. It. Now!!!

Well, what is it?

The next hour was spent with Hermione prodding and casting spells on him, all the while Harry begged not to to go Pomfrey, for his prides sake and the hope it would just wear off.

"Alright...lets talk."
The group stood around in a cluster, Hermione still staring at Harry.

"I wanted to observe because I wasn't sure what this was," she began, but Harry's eyebrows furrowed and he interrupted.

"What do you mean? It's obviously two cat ears, and a tail." He spoke, not bothering to keep the anger out of his voice.

"Well yes, but I didn't know why. The first problem would be why they can't be removed. If it was a simple sticking charm, then the counter should've worked."

"What're you saying?!"

"I'm saying something that could be important to your predicament, but if you want to keep stopping me, by all means go ahead and get a collar on while you're at it." She huffed, evidently annoyed with him. He winced, showing his apologies.

"As I was saying. We've established something is wrong with how they are attached, but what intrigued me, was what you felt." At everyone's frowns, she elaborated,
"If someone sticks something to your skin and pulls, it would hurt. That's why I wasn't quite worried when the boys yanked on your...accessories and you yelled. Now though I am because not only-I think-oh my....Harry I think I know what's wrong." 

"As we knew you would, now please Hermione, tell us how to fix it so Harry doesn't commit a murder...or 4?"

She rolled her eyes but answered nonetheless.

"I'll explain to try and...soften the blow." Harry glowered.
"If this was a result of a poorly done sticking charm, or a botched sticking charm, I'm sure most of the spells I casted would work to remove it, I even tried magic that should try to fix simple botched spells. Even so, the ears and tail would unstick in less than a day. The magic would, wear off, so to speak. I read about it once. Magic is always about intent, we all knew that. The boys intent wasn't to make you a cat, or have these permanent. No matter how badly Ron cast the spell, it would come undone when the intent seemed to be filled, you going to the party. The time you've spent in the costume should've fulfilled the intent of the charm, so if it was a small mistake, I'm sure they would've come off by now, and even if the intent wasn't time based, something like a sticking charm would wear off, the magic would be undone by at most 24 hours. I doubt that's the case though."
She shifted nervously now.
"Harry, the ears and tail have done something I've never seen. They are...apart of you. You feel things. I can simply poke them and you feel it, If I stroke your tail you feel it. It isn't pain from the sticking charm, they have melded themselves to you. That's the thing I can't understand. The body is complicated. I can't see how the ears were able to connect into your nervous system, nor the tail. You don't have cat hearing per say, but....Harry, your tail is moving right now. It's swaying. Which means your brain can send instructions. They aren't just sensitive."
The room was silent. You could've heard a pin drop.
"There's good news, and bad news." Hermione continued tentatively.
"They were placed by magic, so there's only two things that could happen if my theory that the ears and tail have melded themselves to be apart of your body is correct. Your body could attack the unknown magic. If it recognizes the foreign magic, or even if your own bodily functions recognizes something not meant to be there, you can fight it. Bad news and the other option is...I see that chance being slim. If your magic and body allowed it in, I'm not sure if it will see it for what it is, or if it will fight it at all. They might just...stay there." 

Silent again. Harry sat down on his bed and closed his eyes, thinking of this newly contained information. No one spoke, until Seamus broke the unofficial silent game being played.

"So...If I..."
And then Harry felt a hand scratch behind his cat ear, he almost turned and batted the person's hand away as he tensed, but then the hand stroked up and done, before scratching again. Harry hummed, appreciating the distraction from being told he was going to look like a cat hybrid forever. 
Cat!
Forever!
His eyes shot open, and then the laughter begun.
Dean informed him matter of factly, that he could indeed purr, and Harry wondered what the sentence in Azkaban was for murder.
The next day, was going to be hell.