Aging

A scary story told to naughty children

Children are rare to find within Synthacrosia, and hard to deal with.
The Tower exists within Purgatory, and only those who have died arrive at the tower. Once a soul is within the afterlife, they stay forever at the age they were when the died -- in the tower, souls no longer age. This means any child in Synthacrosia would've had to have died in their childhood. It also means they'll stay as a child for eternity.
There was a plan for this, of course. In the early days of Synthacrosia's operation, before Locorin disappeared, a group worked to select and train souls into childcare roles. They would essentially adopt these eternal children, and care for them until the end of time. The childcare givers would try to teach the children, and to help them grow; but as aging was a process that never occurred, maturity was never reached. The children's brains were constantly stuck in a state of regrowth.

Summary

Oh, you don't want to sleep, eh? You know who else didn't want sleep? Old man Jacobsen. He used to stay up as laaaaate as he wanted to, all the time. Every single night. Why, when he was young I think weeks went by without him sleeping. When he was young. But then the Aging got to him. Invisible, horrible creatures, that only come out at night when you're supposed to be asleep, tracked him down. They found him awake, and vulnerable.
And you know what they did?
They made him OLD!

— Childcare Giver on the 4th Floor

Aging is a cautionary tale told to naughty children. It can be any reason, it can be any source, but the point is always the same; if you misbehave, you're going to grow old. You'll start to move slower, you wont be able to run around. You won't be able to jump as high, climb as high. You'll like old people things like wine and beer, and discussing politics.
Generally, these threats will be enough to scare a misbehaving child into acting more appropriately. Sometimes, examples will need to be given. Often times an older soul within Synthacrosia will play along, pretending they were once a young child within the tower, but they acted naughty, and the "Aging Fairies" got them -- or whatever source of aging they choose at the time.

Scary Sources of Aging

Aging can come from any source. It doesnt matter the specifics, as the scary part of the myth is aging. Care givers can easily give examples of older souls within Synthacrosia; they can point at them, and then make up any sort of story for how that person got as old as they did.

Aging Fairies

A classic tale; children who misbehave can draw the ire of tiny, invisible, and malicious fairies. These fairies feed on, and simultaneously hate, youth. They unfortunately have to follow very strict laws set out by the guild of magic fairies: no feeding on children unless the child is misbehaving.

Ghosts of anti-Vigor

Sometimes, when people die, they get stuck. Stuck outside of Synthacrosia. They become ghosts in a perpetual state of unlife, and are drawn to other sources of unrest. Sometimes a Ghost of anti-vigor might be drawn to misbehaving child, and will attempt to drain the youth from the child, in order to regain the life they so desperately desire.

Curse of Age

Children need to be careful about where they go, and who they meet. The Tower isn't a perfect construction; some places within it are more dangerous than others. Some areas and some people carry with them a powerful curse that only strikes at those with naughty intent in their heart. If people aren't careful, the Curse of Age will strike, and they'll rapidly grow old.

Clockwork

The clockwork do more than just try to attack Vibrants . They also have a directive to round up all the bad kids, and bring them to the aging machines. The idea is that really really really old children are easier to manage than young and naughty ones. Kids have to be careful, and remain as good as possible, so that the clockwork never find them.