Spirit: The Crowd

Even though humanity almost completely went extinct, the energy they supplied the conceptual world is still there. Spirits still can feed, grow, and morph on it. Their feelings, memories, and ideas drift anywhere where humans showed up. In places, that were often visited by many people, those things, mix and intertwine, becoming a white noise of energy. And this white noise takes on then the form of the Crowd.
Judging by the classification of Spirits, the Crowds are barely considered ones. Their only power is to manifest themselves audibly and visually (and sometimes aromatically).

Appearance

Depending on the strength of the Crowd, these Spirits tend to take on a few different forms. If they manage to manifest themselves, in their simplest form they show up as a sea of shadows that's in constant motion and yet it doesn't move anywhere. As their power grows, they start to take on more and more mannequin-like appearance. First, they split into two parts, a floating head and a blob forming a body beneath them. Then, the arms and legs start to separate. Next, their torso takes on a more human shape. Lastly, depending on the area they manifested themselves in, they start to "wear" various types of clothes and a caption related to the surrounding shows up on their faces. It could be "shopping" or "sale" in the malls, "photo" or "sights" around the tourist attraction, or "work" in the workplace.
The same thing happens when they also manifest themself audibly. At first, it is just a loud, constant noise, but with the growth of their power, one starts to hear sentences that were once spoken often in the area.

A spiritual commensalism

Although the Crowds are completely passive Spirits, there are some dangers related to them.
First, in case some really negative emotions are also present in their area, they can take on different, more aggressive forms that hide within the rest of the Crowd, such as A Face in the Crowd or Pickpocket.
Second, aside from the potential hostile form of the Crowd hiding within their brethren, other hostile Spirits might want to use them to hide during their hunt. In that case, one has to remember that even if something hides there, it is equally easy to get "lost in the Crowd".

Professor Kostek was running away. It was a really bad day and right now he was chased by a powerful predatory Spirit and a small group of bandits. It was the middle of the town, and as such he had a few possible places to hide. And now, the closest one was a mall. He could hear the human voices behind him and the sounds of heavy breathing from the rooftops above him.
Without stopping, he jumped through one of the broken glass doors and slipped into the Crowd.
Apparently, the Spirit changed its quarry and started hunting the bandits one by one. Panicked and screaming, a few of them entered the same Crowd the Kostek did. Still, he knew he probably lost them.

— Second part of the story is to be found in A Face in the Crowd

Genetic Descendants

• A Face in the Crowd
• Pickpocket

Origin/Ancestry

Humans

Taboo:
Crowds are weak enough that they often don't have any taboos. They don't show up in a once crowded place during the days it was closed, but it is because they try to mimic the flows of energy of that place and not because something compels them to do so.
Reproduction:
Spirits cannot reproduce. Even if, after feeding, the Crowd seems to consist of bigger numbers of Spirits, it is still considered a single entity.

Slowly going extinct

Crowds need human emotions to survive, mainly the emotions related to being in a large crowd of people. Now, as humans almost went extinct, these emotions start to run out. Once it does so, all of the Spirits that need it will either die out themselves or will find another food source, changing themselves to survive.

An obstacle

In most cases, even though the Crowd looks like a solid mass, one can pass through them without any problem. However, there are Crowds that are more material that can force someone to squeeze through them to get to the other side or those that block the path altogether.