You've mentioned that you write in HP. No offense to anyone and I'm not trying to offended (as I, too, write slash in that section so...) first you need to take into account that those that read in HP tend to be much younger and haven't exactly learned that there is more to 'bottom and top' than what they see and/or read on the internet. I've had them do this to me too (usually more in Supernatural though since i make the one no one sees as such the 'bottom), i come back with the example of oral sex. The one giving is tending to be seen as the bottom. When, in reality, it's not. the person with the organ in their mouth is the top because said organ is also surrounded by teeth. That rather switches it around. Oral sex, giving and receiving, is a rather neutral act, not seen as bottom or top because of many factors. The bottom is the one that controls what is done and pleasurable, or painful, sensations that are caused on the so-called 'top' in the situation. The same goes for many other acts like it. There is no real 'bottom or top' in anything unless you are doing a D/s or BDSM situation of some kind and the line is made very clear who is what. Other than that, they are interchangeable.
As for the emotions... again, I mean no offense, but a great many in some fandoms, especially the ones that cater to those that are younger, don't 'get' the emotion thing. Emotion is a hard thing to convey in so many things, be it fanfic or original. In slash, it seems to be harder than in het because so many don't understand one very undeniable 'truth'; males and females react differently to emotional things and show emotion a different way. For example, a 16 year old Harry is not going to run out of a room screaming and crying when confronted with something. Yet I've seen it portrayed that way more than i care to enumerate here. They also don't realize that how beings were portrayed in the books is very different than they were in the movies. Nor do they take into account, using something you said you write, that characters like Sirius were not as well developed as ones like Hernoine or Ron. Sirius was a rather minor character in both the books and movies, with little character development as opposed to other ones that were more of a 'main character'. So how you portray them is your interpretation of what you saw/read. Nor is it right, wrong or indifferent. When there is no real background of development you have to create it to have a good story. Just because yours doesn't agree with what they interpret doesn't make it wrong. OOC, in the case of the more minor characters, is in the eye of the beholder. They just tend to get pissy when you don't do things according to the way they see the world and, for those, stick up your middle finger and tell them to spin on it.
All in all, it comes down to one thing... It's your story to do with what you want. If they don't like it, they are free to shut the page and move on. Their reviews, too, can be easily deleted here. Beyond that, consider the mentality, roll your eyes and move on!