The good, the bad, and the almost irrelevant. They are the miscellaneous characters that are there to answer that one question, explain away that one plot hole, assist in adding development to that actually relevant character, or give that good (or bad) advice. We usually never learn their names. They are there and they are gone as soon as they serve their purpose often never to be seen again. They may not be the most memorable but definitely have a role to play. If the "No Image" picture is used, it means that the particular character has only been mentioned and has never physically appeared.
The Thirteenth House
Chapter 1
Masked Leader
They are the leader of a masked trio convening in an unknown chamber during the book's opening scene. The leader insists they need to choose "the next vessel" because "the entity hungers." They threaten the others with excommunication if they don't find said vessel.
Masked Dissenter
They are one of the masked people discussing the leader's plan to bring in a new vessel. They don't think one vessel will be enough to satisfy "the beast," as it grows hungrier every year, and they would rather "return to tradition."
Masked Thinker
They are one of the masked people discussing the leader's plan to bring in a new vessel. They're worried about what will happen if they perform a ritual without the required twelve people.
Strange Form
Her character model resembles Azalea from Kindred.
Club President
Her character model resembles Candy from The Holiday Bakeoff.
Sore Loser
She also appears in Chapter 4 as "Giddy Student." Her character model resembles a version of Winter from Better Off Wed.
Robed Partier
He reappears in the next chapter as "Suspicious Partier." His character model resembles Seth from Immortal Desires.
Chapter 2
Professor Summers
She is one of your teachers at AHU but is shown to be lazy and offloads the majority of her responsibilities onto Matthew, justifying it as she teaches harder classes and a TA can handle a 101 class by himself. Her character model resembles Lupe Montoya from Filthy Rich.
Matthew
He is Professor Summers' TA. He mentions having been part of a strict club and was almost expelled for writing his thesis paper on a controversial topic, causing you to suspect he could be part of the Zodiac Society. In a premium scene in Chapter 4, it is mentioned his Zodiac sign is Virgo. His character model resembles Brooks Barrett from Kindred.
Chapter 3
Coach Bud
His character model resembles Coach Rojas from Hot Shot.
Chapter 5
Spa Receptionist
Her character model resembles Dr. Rosa from With Every Heartbeat.
Chapter 6
Lisa Vanderbjörn
Lance's mother who you discover is part of the Zodiac Society. Her character model resembles a version of Beth from Better Off Wed.
Liam Vanderbjörn
Lance's father who you discover is part of the Zodiac Society. His character model resembles Dad from Best Served Haute.
Annoying Lady
Her character model resembles Margaret Montjoy from A Very Scandalous Proposal.
Jovial King
His character model resembles a version of Edmond Julivert from The Princess Swap.
Sneaky Noble
A member of the Zodiac Society who shared information with Calista, before confronting her on the believe that she betrayed him. Depending on your choices in the following chapter, he gives your friends a thinly veiled threat that the Zodiac Society is always watching them and implies that your parents were members. His character model resembles Cecil from The Princess Swap.
Chapter 7
Gossiping Student
Her character model resembles a version of Winter from Better Off Wed.
Buttercup
Her character model resembles Sultan from Untameable.
Stephanie
She first appears as "Actress." Her character model resembles Bethany Delgado from Crimes of Passion.
Mr. Schwartz
He first appears as "Director." His character model resembles Theodore Vitale from Inheritance.
Auctioneer
His character model resembles a version of Lucky from Better Off Wed.