The image of a loner tends to be split in one of two camps. Either you'll see him/her in a romanticized, Hollywood way - the silent, mysterious hero with a tough front belying his sensitive and poetic nature. Wandering through the streets, contemplating the dark truths of life, perhaps brooding over a deep love once lost yet ready to snap into action to protect a stranger from a gang of criminals a la Batman.
Or you'll see him as the newspapers tend to portray loners - disturbed antisocial maniacs on the verge of wandering into a primary school with an AK-47 and taking out their frustrations on innocent children. Psychopaths with little empathy who don't understand human emotion and avoid making what they see as pointless connections with others. Or, similarly, afraid of opening up to outsiders for fear they get an insight into some deadly terrorist plot.
These people are all around us and we often judge them mercilessly. We'll notice them in a cinema and think "Gosh. Friendless weirdo. Imagine enjoying an activity which requires silence and complete external focus by yourself." Or see someone reclining at the beach with a cold drink and a book and think, "What's he reading, Mein Kampf? Why isn't he surrounded by other people who are also sunbathing? Psycho." Or clock one in a restaurant, forlornly picking at their food whilst toying with the idea of ramming the fork into their own eye (we imagine).
I'm more the kind of person who'll be chilling out by myself in a public place, rather than the life-critic eyeing me up before deciding I'm best avoided. I guess I'd describe myself as a bit of a loner, and the reason for this is mostly; I enjoy my own company. I need lots of time alone to recharge, to put my thoughts in order and regulate my emotions. That's not to say I don't enjoy being with other people. Of course I do, we all do, socialising is a necessary function for humans, we are a social species. I like people. I just don't want to interact with them 24/7.
So when you see me in a cinema, or a restaurant, or at the beach, or on occasion a night-club (that can look a bit weird admittedly), I'm not miserable. Far from it. I'm enjoying the movie, or the Asian food, or the sun-rays, and absorbing the experience in my own time without having to worry whether a companion is enjoying it as much. I'm content.
Of course, not all loners are that way for the same reasons as me. For some, social isolation is not a choice but rather forced upon them by circumstances beyond their control. Some have crippling social anxiety caused by traumatic life experiences, and lack the confidence to reveal themselves to others. Others have conditions like agoraphobia which makes them afraid to be in open spaces , major depression leaving them unable and unwilling to connect with others, or possibly forms of Asperger's or Autism which gives them greater difficulty understanding and enjoying personal relationships.
Either way, it seems clear that many people who live with a degree of social isolation do so not because they see others as inferior and unworthy of their time, nor that they are plotting to commit brutal psychopathic atrocities in crowded places, and (sadly) nor that they are some Harrison Ford-style anti-hero protecting the innocent populace from vicious goons armed with nothing more than a quick wit and a karate black belt.
More likely, the loner is just a normal person who prefers to hang out by themselves either because they really enjoy it or they're not ready for social interaction just yet. Therefore, it's important we practise tolerance and understanding towards them, and not treat them as some kind of dangerous alien. See them as just another shade of colour which makes up the diverse rainbow of human nature. It'd be boring if we were all the same wouldn't it?