A demigods is a human who is born with a divine spark. When this spark is activated, the individual becomes a being with incredible power. It grants them a number of abilities, including immortality, near-invulnerability to mortal weapons, robust healing factor, and vast magical power. However, their most important power is the ability to travel between different realms in the multiverse when normal humans are unable to do so. This divine spark is part of an individual's soul, and is found at random among the population. Therefore, they are the equivalent of planeswalkers to the people of the multiverse, chosen by the gods to defend the various realms from outside threats (worlds ruled by demons, creatures from the space between realms, etc)
The demigods function as an organization that operate within a hidden realm only inhabited by their kind. This organization has the technology to locate children across the realms who possess the spark, which manifests at the age of puberty. When a child is found, demigods are dispatched to that realm to claim this child from their family. Through an ancient pact with humanity, the gods decreed that all children born with this spark are laid claimed to by the walkers in exchange for protection against evil forces. This is the only way that demigods replenish their numbers. This pact also prevents demigods from interfering with baseline humanity and civilization, except in specifically extreme circumstances that have to do in defending the realm from outside forces.
From a practical standpoint, it would make sense that this organization would promote close cooperation among their members. demigods would work in teams to battle threats when they arise. However, I want them to usually operate solo and alone for most major and minor threats to the realms. It should be very rare for demigods to operate together or be in one place at the same time outside of their base realm.
How do I make this happen?