Tris was a man of action. Once an idea occurred to him, he had to act on it.
So that night, after Theodore and Blaise had fallen asleep, he opened his eyes, having only pretended to sleep. He walked to the wall and murmured a spell, then silently melted into its shadows.
Over the holidays, apart from brewing Magic Spirit Potions, he had spent almost all his time studying and practicing Shadow Magic and Sectumsempra.
The former was the most complete system of magic he currently knew, comprising several spells that could be used in combination. It was not particularly difficult and offered excellent protection.
The latter was a powerful offensive spell.
Although he had obtained more than one powerful spell from Voldemort, none matched Sectumsempra's strength while also allowing Tris to cast it silently at his current level.
Having mastered Shadow Magic as a complete system, Tris had become increasingly adept at using it.
Without a sound, he moved far faster than he had when stealing the Philosopher's Stone a few months earlier. In no time, he was outside Hogwarts Castle.
From a distance, he saw a dozen or so tall figures gathered at the junction leading toward Hogsmeade. Draped in black robes, they seemed barely corporeal, floating weightlessly yet exuding an intense sense of oppression.
Dementors!
These Dementors clearly had not detected Tris.
According to what Tris had read, Dementors could sense living creatures' emotions. The clearer and more intense an emotion, the easier it was for them to detect.
But with his Thought Maze, Tris kept every fluctuation of his mind, soul, and emotions completely contained.
The Dementors could sense neither his emotions nor the fluctuations of his soul. With his body also concealed in the shadows, their failure to notice him was hardly surprising.
*A dozen