Okay it's kinda implied in the show that Kaijudo is either passed down in the family like with Ken and Isao or you are spotted with great potential by a member in the Order like with Ray, Allie and Gabe
Either way you are tested by the Order in how to handle mana and how quickly you can pick it up in one day, if not you're memory is erased.
Here are my takes on how I think the Masters got recruited:
Hector
For Hector I feel like he got recruited from his family
For this reason it's because I believe working with Fire Creatures takes a long time especially with how uncontrollable and are very destructive they are in nature
I feel like Fire Specialist are mostly those who were trained by family members who learn how to fight with such fiery creatures and have a passed down teachings and certain practices
It's also implied in the show there can be certain side effects when training in certain civilizations, shown with Allie when letting darkness taking over
When working with Fire Civilization you must have a literal spark in order to train with Fire Creatures specifically
However that spark can take over and become in it's essence rage and a destructive force
Hector learned from family how to control and be more tame when working with Fire Civilization
I think that's why his character is so calm and tame because he had to learn to control the fire within when he was an acolyte himself
When it comes to families who train in Fire, most often than not all children are expected to train and learn the teachings
I'll get into it in another post, but when it comes to some families, especially those held at a high standard because of their long history with the Order they are most likely grew up with Kaijudo their whole lives as children
Hector's family was one of the few that had such a high standard that he grew up with Kaijudo his whole life and expected to carry on a certain legacy of his family
Nadia
Nadia was spotted by a Water Specialist
I feel like when those from the Order spot outsiders to join they usually will spot characteristics with civilizations
So with Nadia she was mostly likely spotted for her keen desire to keep expanding her knowledge, her control over her emotions and ability to be flexible
It's not just characteristics associated with civilizations though, it's also showing bravery and being able to face the unknown especially when it comes with dealing with dangerous creatures
With Nadia she was spotted off the streets and used her smarts to get herself around
But she also expressed a level of justice and most likely got spotted when she was defending someone
Kimora
He was also spotted
With nature, you have to express commitment and loyalty
It's like when you take care of plants, they take time and patience to keep them alive and require compassion and a sense of duty
However Kimora was initially spotted by showing characteristics of bravery and loyalty
It wasn't until after he was officially joined the Order that he began showing his strong alignment with nature
I feel with nature as well you have to show a sense of community, a lot of Nature Creatures seen in the show are most often than not with a group, like with the Quillspikes or Bronze-Arm Tribe
As a acolyte, he trained a lot in groups, helped those around him and thrived in being with others
It wasn't until Kimora showed more of these characteristics that he was more committed to a Nature Civilization training
Jaha
She was definitely recruited by family
Like Fire, it's another civilization to master, you can easily give into the darkness and become corrupt
Those who train in Darkness Civilization have to be guided by specialists and learn how to not let it take over
However not just anyone in the family can be trained compared to families who train in Fire
Children of families that train in Darkness are hand selected and picked from the very best
The Darkness can easily manipulate you and families themselves will often do their own tests to their children to see if they can handle it
With Jaha, she absolutely had to prove to her family she can handle it, showing how cunning and resourceful she is
Just like Hector, Jaha also has a legacy to carry on from her family
It's why Jaha takes up Allie as her protege, teaching her the ways of how her family taught her since Jaha wants to pass down what her own family was taught
Nigel
It can really go either or for me
Spotted or from a family
But because he's absolutely never strays from the rules, I feel like he does come from a family that comes from some sort of line of Light
Not a very high standard one like Jaha or Hector, but definitely a more recent and small family
Nigel was held up at a standard from a very young age
He was taught from day one to follow the rules and can never stray
From trauma of being taught these strict ways and forced into the role it's why Nigel betrayed the Order as well
He can't bring himself to go against what he was taught his whole life because it's so foreign and most likely frightens him if he strays
Nigel also holds himself at a high standard and even though he cut ties with his family, he still can't help think about the disappointment and guilt if he strays from the rules
So yeah here are some Kaijudo Headcannons and how I think the Masters were recruited, let me know what you think!