While Luna could not just leave the young witch out here, on the ground, curled into her pathetic little ball, neither did she know what she was supposed to do.
If she had known what Merope had truly done, what she had done to Tom Riddle Sr., she would not have lingered in any way.
The blonde witch might have offered comfort in the past to Hermione, even after the other witch mocked her, to her face and behind her back. She certainly tried to comfort Ginny, and most definitely Harry. And yet, even Luna Lovegood could not bring herself to reach out and try to soothe Merope's maudlin state of mind.
So, instead, she simply sat by the other girl, her hands in her lap. "No one deserves to be alone all the time, not even one of the heirs of Slytherin."