(This is a modern au where magic still exists but everything is to date and the houses are instead dorms)
Luna had had a rough day, she accidentally messed up a potion in class, at night she woke up to get a glass if water, she was greeted by the cold dampness in her pajama bottoms as she was embarrassed as she started to sob causing Ginny to wake up in concern sitting in the damp bed, which she realized before sitting down "hey hey babe what's wrong?" Ginny asked stroking Luna hair gently, just like Ginny's mother used to when she had bad dreams as one pointed to the damp bed and ginny felt sorry "awe babe did you wet the bed, dont cry its ok, I'm not mad.. " luna felt a bit better but couldn't process it as she went un thr hug ginny crying harder as ginny patted her back "there there its alright.. I have a idea babe.." ginny grabbed her wand using a spell to create a pull up "you wont be wearing 24/7 yet, but if you wake up wet 3 times your gonna wear diapers, if you make a stinky in one diapers, and you get to be my little baby" luna blushed and liked the idea but hid her excitement and ginny cleaned and put new sheets kn and luna took a shower and changed her into new pajamas and went to lay down ginny went flipping her on her chest and pulled back her waistband to see if she had her pull up on
(Morning)
Luna woke up to a foul smell and got excited checking herself, sure enough she had a loaded diaper as ginny went over and luna hid her excitement "oh my baby you made a huge stinky, you know what that means" luna got excited as Ginny summoned everything like onesies and plenty if diapers "from now on only baby talk ok, and the potty is officially off limits for you, understand?" Luna nodded and ginny took her laying her on a changing mat changing her into a thick diaper sho luna was forced to be held or crawl "there's my little moon ~ yes you are yes you are!" She cood and luna giggled