Beowulf journaling

What is a grendel? Someone who is mean, maybe shunned, or someone you don't get along with. But why don't we get along with these people? Do we just disagree on things? Or are we not interested in the same things? But this doesn't really explain why this person is a grendel in peoples lives. I mean, I get along well with people who fit under those categories. I feel like there are some people who are just simply mean. No matter the situation, they are pretty much in a bad mood. No matter how nicely you ask them a question, they always spat some maliciousness back in your face. No matter how genuine you are, they ridicule you. My simple, yet somehow complex question- why? Why are these people so cruel? Shouldn't there be a simple explanation? But I do not understand why they have to be this way. Why would they respond to people in these ways? Do they not see that they get a negative reaction from it? That's why it has to be deeper than that. We do not know why, and that is why we are to continually do right by them, even though we expect the same awful reactions. It seems so unfair, which is why i like to hope there is a reason for it. Maybe that person has a bad home life, or has/was always shunned or rejected. I am not trying to justify their grendel qualities and actions, but maybe see life from their perspective. Writing this all down here is one thing, but actually applying it is another. It can be so hard to continually try and care for people who constantly reject you. Maybe they just want you to leave them alone. How do you know how close to the line they want you to come? By just leaving them alone, would you be proving there point of not caring, or would you just be pissing them off by pestering them? So i guess i really have to questions, how and why?