A dark addition to the world of Harry Potter, Dementors are vile and loathsome creatures, whose only objective is to suck every single happy feeling out of humans. As MuggleNet, the most comprehensive guide to J.K. Rowling’s novel, puts it
Dementors feed on positive human emotions – happiness, hope, excitement. Their mere presence sucks every happy feeling or memory from any human present, leaving only cold dark despair in its place. The worst experiences of the victim’s life will flood through them as everything positive is stripped away.
Oh, and these foul beings absolutely love granting humans their special gift, the Dementor’s Kiss. The recipient of a Kiss will get their soul sucked right out by the Dementor.
Fending off a Dementor requires summoning a Patronus, guardian of the summoner’s soul and happiness. The Patronus appears as a silver glowing animal, the animal form dependent on the summoner, and is formed from the ethereal positive feelings of the summoner. It then barricades itself between the Dementor and the summoner, thus protecting the summoner from harm.
And why in the name of Merlin’s pants am I talking about Dementors and Patronuses?
Because Dementors truly exist in the real world, just not in the form described above.
The real world Dementors don’t wear cloaks nor do they have a horrible visage. They actually look a lot like us. They can be your parents, your teachers, your friends, your colleagues, the stranger you meet in the park or your nice next door neighbour. Anyone at all.
Armed with their happiness-sucking ability, they proceed to dampen every daring dream you have, every glorious goal you strive for.
“Oh you’ll never make it.”
“It’s just too hard, isn’t it?”
“You’re a failure, and you’ll always be a failure.”
What you need to do is slowly disassociate yourself from these people. Or ignore them. Whilst it’s hard to do for certain people (like your parents), you can do something to help yourself: summon a Patronus. Just like a true-blue wizard or witch, fill yourself with the happiest memory you can recall the moment you feel the cold despair emanating from these soul suckers. Then blast every cell in your body with the euphoria, forming an invisible barrier, thus rendering you impervious to their debilitating words.
It’s sometimes hard to summon a Patronus under the best of conditions, let alone being continually besieged by these unbelieving, depressing people around you (or descended upon by tons of Dementors in Prisoner of Azkaban). Just practise bringing up happy memories and feelings, hold them in your mind for a while, and soon you’ll be able to summon Patronuses as instinctively as the boy who lived.
Waving a wand and exclaiming “expecto patronum” is optional.