You will need a peggy to get there.
Anathema's lives on the Isle shaped as a ? I found her on the top of it at the beginning of the question mark, but please note, I have heard from players that she is known to wander.
Anathema Doesn't believe that you are real in fact, she believes that you're a figment of her imagination. A voice in her head, and that no one can live on the isle that she's at but her!
Anathema thinks she is going to challenge herself. ( talk about someone who's twice as nuts as that lady on Rain!)
To prove that you're real, you're going to bring her stuff that's not found on any of the cloud isles.
First you give her a chunk of Obsidian. She tells you that you have three more tries.
Next, give her a Giant coconut, she tells you that its a pun of sorts, but nice try. Two more to go.
Next up, a bunch of grapes from Aesop Isle. She quickly senses the defeat coming, not to mention a pun of 'Sour grapes' attitude.
Next give her a Candy Cane from Christmas Isle. Tell her that after she takes a bite of the candy that she interacted wit it meaning its real, which dawns on her, the reality of her not being alone on the isle anymore. You won that challenge!
Reward: 50 silver linings and 100 QP