Betrayed

I've been thinking, as I often do, on abstract concepts of humanity, specifically the emotional ones, specifically the enduring negative ones such as mistrust and distaste. But today I'd like to focus in on betrayal and why we hold grudges. I find it interesting, in my observances of others, the sheer variance with which the people around me hold grudges. You have people who feel slighted at every turn, people who flip on some people and not others, people who are reasonable in their grudges, and people who just can't hold a grudge to save their life.
I can't know, not do I pretend to know, about why people do that. There are over 7 billion reasons I'm sure. But I can give my opinion, and I most certainly shall!
Those people who feel always slighted are slightly paranoid and irresponsible in my opinion. They blame their problems on others, yet its their own life, and they are the ones in control of it. These people are the first to blame someone else, but its ok. Its their personality, so I can't change it. It simply is.
The people who are worse are those who are seemingly random in their mistrust and grudge holding. One of my friends does that, and her only reason has to do with the fact that he looks shady. Looks. Yet she trusts me, and I don't claim to be a saint. I occasionally use others if it benefits my interests, good as those usually are. And they're fine with me doing that. I don't understand it.
The reasonable people are the best. With them, you know what to expect, and its all fair. They may not like you, but at least you know what you did.
The oddest people are those who don't hold grudges, and I'm proud to say I'm odd. I rarely get mad, but when I do, it never lasts longer than the next day or my next encounter. If you raise my ire, you have to seriously screw up. Multiple times. In a way that is detrimental to not just me but others. I'm very optimistic like that and I expect everyone to be able to change for the better and respect each other. It means I'm very gullible, but oh well. Again, its not good or bad, it just is, and in this case, is me.