This morning I had a thought provoking post about the concepts of power and responsibility and the dangers of keeping vital information from people who need it, especially when they don't realize they need it, and how Harry has grown over the books from all the secrecy bs in the early books that would have eventually gotten Murphy, Molly, Butters, and all his other (mostly) vanilla friends killed if he had kept it up, but the forum seems to have eaten it.
Also, I'm not giving Kim and Susan a pass on anything. Both of them made their decisions and had to deal with the consequences. By the same token, Harry does not get a pass for withholding vital information from Kim and Susan. They made their decisions based on what they thought they knew. He doesn't get a pass for hiding the realities of the supernatural from Susan to the extent she thinks old horror movie tropes are enough to protect herself when she invites herself into a vampire's den. He screwed up. Repeatedly. He goes on and on in the early books about how normal people need to stay away from the supernatural and how dangerous it is, and also about power and responsibility. He has power, he has knowledge, by his own logic he had the responsibility to use it wisely and in these two cases in particular, failed to do so. Kim and Susan were already involved with the supernatural. Susan didn't understand the true extent of the danger, and Kim...the whole scene with Kim, in particular, struck me as someone who knows they need help trying the only way they can think of to get help from the one person who can help them, but who refuses to help almost by default. Harry knew she was doing something above her skill level, basically told her she was an idiot for even trying, and apparently expected her to follow his orders and give it up on the spot. Is it any wonder she lied about what she was really doing? Early Harry has a lot of annoying complexes...Hero complex, Mysterious Wizard complex, I Am Always Right complex, I Am The Only One Who Can Do It complex...not to mention an overabundance of pride and even arrogance. Frankly, while I enjoy the books, Harry, especially when looked at objectively early on, is a complete ass. He gets better as the books go on, but he makes tons of mistakes on the way (and ends up paying for them too, for the most part). Character development is a good thing.