Why Would the Guardian Spirit Act Like This?

"Expecto Patronum!" Young Dumbledore swung his wand, drawing a circle before him.

A silver phoenix Patronus flew from the tip of his wand. With a beat of its wings, it shot high into the air, swiftly adjusted its wings, and dived toward the opposite side of young Dumbledore.

On the other side of the silver-glowing magical energy field stood a tall, gaunt figure in a cloak;

It floated in midair, its exposed grayish-white skin covered in slime, giving the impression that its flesh was rotting. It was unmistakably a Dementor.

The phoenix Patronus swooped at the Dementor, driving its long beak viciously into it before swiftly shifting position and raising its talons to strike again.

The magical energy field was also formed from the Patronus Charm. The Dementor had nowhere left to retreat and could only struggle futilely, doing its best to evade the phoenix's talons and beak.

"It seems to be the same..." Young Dumbledore said thoughtfully. "Let's try something else..."

With a light flick of his wand, the phoenix Patronus dissipated.

The Dementor probably wanted nothing more than to escape. It circled the magical energy field, trying to find a breach through which it could flee.

Young Dumbledore glanced at the Dementor, raised his wand to his temple, and finally began muttering under his breath, as though changing something.

Wizet could tell that young Dumbledore was casting mental magic;

As for what exactly he intended to alter, Wizet could only infer from the situation—young Dumbledore was using mental magic to change the Patronus's form.

Wizet reached this conclusion because he could do the same;

A corporeal Patronus displayed this way usually required advance preparation and expended mental energy to maintain the altered corporeal Patronus;

Wizet's circumstances were rather special. He possessed multiple Animagus forms, which meant he had