Ron would be full of anger and sorrow. He might direct his anger at himself, thinking he could have done more to protect Harry. He would probably become more reckless in his actions, trying to avenge Harry's death. His relationship with Hermione might also be strained as they both deal with their grief in different ways.
At first, Harry would be in disbelief. He would think it was some sort of joke or misunderstanding. But as the reality sets in, he would become a bit of a loner. He'd still have his sense of right and wrong, so he might continue to fight against the dark forces on his own, all the while hoping that his friends would come to their senses and realize they made a huge mistake in betraying him.
He would probably try to figure out what went wrong. Harry is a curious and determined character. He might start to recall recent events to see if there were any signs of his friends' discontent. He could also try to reach out to them, either directly or through mutual acquaintances, to ask for an explanation.
Hermione would be heartbroken as well. She would likely try to find a way to bring Lupin back, delving deep into the library's restricted section for any possible spells or solutions. She would also be the one to comfort Harry and Ron, using her logic to try to make sense of the senseless loss.
Hermione would probably be quite understanding. She might see it as an opportunity to promote equality and acceptance in the wizarding world. Ron, on the other hand, would likely be a bit more awkward at first, but would soon come around to support Harry once he realizes it's not a big deal.
The Weasley twins would absolutely love it. They'd see it as a great opportunity for more pranks. They might magically enhance the dress to do all sorts of crazy things, like change colors or play music, all while Harry is trying to go about his normal day at Hogwarts. And they'd be very protective of Harry if anyone made mean comments about his dress - wearing.
Harry might react with fear. He could be traumatized by the experience and be constantly on edge, jumping at the slightest sound. This fear could make him more cautious in general.
He might initially be confused. Harry could keep trying to engage with his friends as usual, not really understanding why they are being cold towards him.
Luna would absolutely love it. She would probably join Harry in wearing unique dresses and trying out new makeup looks. She might even introduce Harry to some magical fashion items that she has discovered. Harry's friends from the DA would also be mostly supportive, seeing it as a form of self - expression and a way for Harry to break free from the traditional wizarding world's expectations.
He might be very sad at first. Harry has always valued his friends, so being forgotten by them would be a huge blow.
At first, his friends would be shocked. Hermione might think it's some kind of dark magic at first glance. But as Harry shows them what he can do, she would start to analyze it scientifically. Ron would be more awed. He'd be like a kid seeing a new cool trick. They would both support Harry in exploring this new ability, but also be a bit cautious as they don't fully understand where it comes from or what the implications are in their wizarding world.