After penning the most successful children's book series ever, J.K. Rowling has stepped into the role of cheerleader , advice-giver and Twitter-mum to a generation raised on Harry Potter. The author is known for dispensing words of wisdom and heartfelt support to her legions of fans. On Monday, the Brit showed her compassion again in a sweet Twitter interaction with a fan battling the demons of depression.A Brazilian teenaged girl named Marina asked, "could you please teach me how to scare the dementors that have been living under my bed? i'm tired of being sad all the time [sic]." Rowling replied just eight minutes later. "They're bothering a unique, valuable human being who deserves happiness," she wrote. "Ask for help. Don't fight alone. Big hug."It appears Marina is already feeling a little better. She tweeted back, "oh god im going to sleep now with a big smile on my face [sic]." Then a fellow Potter fan tweeted to Marina and Rowling, "And don't forget to eat chocolate every now & then!" Rowling said, "Wise words." (May we suggest some chocolate frogs?" While the writer's kindness is stirring, it's not exactly surprising.J.K. Rowling has spoken freely about her own battles with clinical depression in the past, and sent uplifting messages to fans over the years. Dementors, the deadly, soul-sucking creatures that dim the light of whomever they descend upon, are widely thought to be emblematic of depression. And although they're fictional creatures, their inventor certainly has some amazing real-world wisdom for battling them.