This common species of snake is not known to be aggressive, but can administer a surprise strike if provoked. A comforting thought for when you summon your Adder Patronus. After all, it's always important to defend yourself.
Written by the harrypotter.com team
“The Patronus is a kind of positive force, a projection of the very things that the Dementor feeds upon - hope, happiness, the desire to survive – but it cannot feel despair, as real humans can, so the Dementors can’t hurt it.”