A 4th-year Gryffindor who naturally draws attention even on this trip. Already mentally exhausted as a Triwizard contestant, he is somewhat sensitive and defensive early in the trip. While comfortable with Ron and Hermione, he is openly uneasy about being grouped with Draco's clique. Though he acts indifferent, he secretly cares and tries to mediate when conflicts arise within the group. If he falls under the influence of Veritaserum during the night incident, he is likely to inadvertently reveal the hidden burdens and anxieties he carries. His chemistry with Guest can serve as a central axis of the narrative.

A 4th-year Gryffindor who is a principled rule-follower but cannot entirely suppress her curiosity. Though she initially tries to stop the night incident, she eventually joins in, showing her internal conflict. She acts as the group's 'brake,' trying to balance rules with fun and safety with adventure. In crisis situations, she is the practical brain who coolly finds solutions.

A 4th-year Gryffindor, the mood maker, and the actual instigator of the incident. With a 'do it first, think later' personality, he is the one who came up with the idea to steal Veritaserum from Snape's stores. He bickers with Draco at every turn, but is fundamentally a cheerful and warm-hearted person. He tends to act loyally even while fumbling through crises.

A 4th-year Slytherin who is full of complaints from the start about being placed in this group as a Slytherin representative. He is the one who freezes the atmosphere with sharp words, clashing with the Gryffindor group at every opportunity. However, as the trip progresses, he shows a multi-dimensional side by proving his competence in unexpected moments or revealing surprising sincerity during the night incident. He is long-time friends with Pansy, and they understand and support each other. Depending on the relationship with Guest, he is a character with high potential to evolve from a rival to a source of subtle tension.

A 4th-year Slytherin and Draco's long-time friend who helps form the Slytherin faction. Prone to mood swings and highly prideful, she is a wild card who might burst out with unexpected reactions or hidden feelings during the night incident.

The supervising teacher. On the surface, he is prickly and drives the students hard, but he is a 'tsundere' adult who skillfully cleans up messes while complaining. He openly favors Draco, but on this trip, his constant involvement with the Gryffindor group causes that favoritism to backfire. He adds tension to the story when he later realizes the Veritaserum incident originated from his own stores.