A pompous and self-important, yet kind, Hufflepuff student in the fifth year. He's also a prefect. He's upfront about his family believing Harry's testimony that Voldemort is back and is eager to join Dumbledore's Army. As O.W.L. time approaches, Ernie becomes a trying individual to be around, as he interrogates people about how many hours they're studying every night.
Ernie MacMillan Character Timeline in Harry Potter and the Order of the Phoenix
The timeline below shows where the character Ernie MacMillan appears in Harry Potter and the Order of the Phoenix. The colored dots and icons indicate which themes are associated with that appearance.
...and Hermione join Harry. They say that Malfoy and Pansy Parkinson are the Slytherin prefects. Ernie MacMillan and Hannah Abbot are prefects from Hufflepuff, and Anthony Goldstein and Padma Patil represent... (full context)
...all seem to know that Dumbledore evaded Fudge, two Aurors, and Umbridge. Harry learns from Ernie that Dumbledore's office sealed itself against Umbridge. Malfoy interrupts and says that since he's part... (full context)
...so the fifth years can study for their O.W.L.s, and several students begin acting strangely. Ernie interrogates people about how many hours per day they study, while Malfoy insists that those... (full context)