Edinburgh's special forces preferred hiring rankers with special elemental affinities.
Krista, Rupen, and Lambert were hired into the Blood Punisher force for the same reason. They were then groomed by the kingdom's elite rankers and given top-tier resources to develop their skills.
Such rankers were the team's asset. They held the potential to make difficult tasks reach their conclusion with sufficient ease.
Drin's shadow element was well suited for shady jobs that would usually be handled by the special forces. Even Kev was interested in bringing Drin under the kingdom's thumb for the same reason.
Meera wasn't interested in the job at first. It was Kev who told her she should take Rehaal's offer to free Drin from his current responsibilities. Upon thinking about it, it made sense to her as well.