One of the most critical points in a person's life is the point they manifest magic. This point in time dictates the form and methods that they access power, but also the flexibility of how they use it and the strength of their abilities.
Once a power manifests, it usually remains set but that doesn't mean it is static. Mages can learn new spells and talents can refine or strength their power, but usually every skill or ability to follows will be related to the first manifestation.
Trauma Breeds Power
The strength of the power is highly influenced by the trauma of the manifesting event. If the manifestation happens during periods of high stress, the resulting power typically is strengthened by the need to survive. Likewise, if the trauma is relatively minor, then the abilities are usually less survival-oriented and have more subtle effects.
⚠️ SPOILER: From this point, this page reveals spoilers for Sand and Blood. ⚠️ SPOILER: From this point, this page reveals spoilers for A Cup of Soup.
A good example is Sand and Bone where the abuse Rutejìmo experiences from the Shimusògo clan was intentionally crafted to ensure he and the other teenagers would have the greatest chance of producing a strong, survival-based power.
In contrast, those who live in much more comfort have abilities related to their lives such as the events in A Cup of Soup. For some, this can be traumatizing if they were hoping for more “interesting” abilities.
She stood up as her daughter came down the stairs, one step at a time as if it was the first time she was walking.
The smell of flowers drifted through the kitchen first. It was the same scent as her favorite flower, the Lady Pamran's Silver. The smell grew stronger as Karen inched into the room. Her black hair fluttered with silver petals, the curls of green stems curling around her hair and pulling her long hair into two tails.
Mabel's mouth opened with surprise.
Karen whimpered softly and looked up, her brown eyes shimmering with tears. One of the leaves uncurled around her right temple and wrapped around her hair, pulling it back from her face. It was the same maneuver Karen used to do as a little girl, but she used her finger then.
Over the years, the understanding how trauma affects how the power manifests means there is a cultural effort to maximize or pick specific powers. In the desert, this is considered to be critical to survival such as the events in I Will Hurt You Only Once but along the coastal areas, the practice is discouraged or even illegal such as the events in Illegal Traditions.
Second Manifestation
A number of the population, about one in a hundred thousand, will experience a second manifestation during their adult years. This is usually triggered by a harrowing experience with a resulting power being more survival based. It is almost unheard of a second manifestation happening without a traumatic event. Those who live easy lives rarely need additional powers.
When a second manifestation happens, the power may not have any relation to the first one. It could turn a talent into a mage or give a second talent to someone.
Exceptions
⚠️ SPOILER: From this point, this page reveals spoilers for Flight of the Scions.
While almost every single person manifest powers, there are exceptions. Unlike the Emerging Wizardry quote below, this happens roughly in one in a million teenagers. It is harder to measure since many powers have subtle effects or never impact someone's life, but they still have power.
In ninety-five out of a hundred people, the first magical manifestation of power happens by the age of thirteen. — Emerging Wizardry (Volume 91, Issue 6)
An inert person, also known as a barichirōma, is someone who has absolutely no ability to change, detect, or use magic. This does not prevent them from being a passive member in a telepathic communication but they cannot initiate or press, only allow their mind to be read and the active member to choose to interact or not.
The best known and documented exception is Kanéko who, despite being talented at visualization and understanding information, had absolutely no ability to produce magical energy.