First of all, drop the attitude - now. "Why don't people want to be my friend when I look down on them for their interests???" <-- That's the problem. Try focusing on finding people with your interests instead of hanging along on whatever popular fandom you can find to be "normal" since people different from you don't seem to sit well with you.
You have to learn the first fundamental rule of online communication: Interpretation versus Intention.
I'm not involved in whatever drama it is you seemed to have stirred, but what I'm getting from reading the comments is that other people interpret your word choice to be rude, but you seem to intend your words to be in a nicer tone. Honestly, you have to type online carefully, preferably using a polite, neutral tone (no slang or your regular speaking vocabulary) with people you don't know before gradually introducing them to your own personal dialect. You have to give people a chance to warm up to you and get a feel for your "voice." If you immediately jump in with your own way of speaking, people are more likely to misunderstand you. For instance, I'm a very sarcastic person in real life, and my tone and word choice reflects that. However, I try my hardest not to express my sarcasm online (especially in the forums) so I lessen the odds of people misunderstanding what I'm trying to say or misinterpreting how I'm trying to say it. On the other hand, when I'm online talking to my friends, I go all out with the informality and slang. It's okay with them because they can, in a sense, hear my voice and know what I mean by it.
Additionally, if you want to be friends with people who follow the Hetalia fandom, you may want to start by joining a few Hetalia groups and asking around to see who likes the same characters you like--and most importantly, not negatively judging people if they like someone you don't. It also helps if you don't refer to them as "nerds" and "geeks," as some people may take offense to those terms.
~witwitch mentioned how you should look for people with similar interests as you. It is quite common to have friendships built up on similar interests. Most of my friends on dA I'm friends with because of our shared interest of Kingdom Hearts. Even though a fandom was our starting point (and honestly, a lot of friends have come and gone), the few who remained are the ones I have formed true bonds with. I wouldn't trade them for anything.
Numerous people bring up a possible communication issue and suggest you should be "nicer." That's a simple fix by carefully choosing your words and asking yourself "Is there any way for someone to take offense to what I'm about to say?" Usually, unless you intend to start a creative discussion, you want to avoid provocation of any sort.
There's nothing wrong with saying what's on your mind, it's just how you word it.
For example, the phrase "shut up." "Shut up" alone is widely recognized to be a rude phrase. Some people consider it whining while others consider it aggressive. Of course, you can toss "shut up" around amongst your friends because, chances are, you're joking when you say it. Online, you can't predict how anyone will ever take your words. Again with interpretation versus intention. Instead of saying "shut up," in the sense of telling someone to stop talking, you should instead politely (or neutrally) ask them to kindly stop talking to you. Or you can simply delete their comment from your inbox and blissfully ignore them. That's also a nice way to avoid conflict.
Basically, you need to be sensitive to others. You need to accept and understand that not everyone online will interpret your words the way you intend them.