Just some ideas that I thought of for the Sleepless universe.
Everyone's lives are completed dictated by the Endless, for the most part.
For example, Agent Mei is already scheduled for failure/execution for being suspected of falling off track. Therefore, his Mission-3 is to aid/train a junior agent, Alice, in completing her mission.
Alice is given the Mission-1 of preventing the execution of at least one of the ARC patients.
Isaac is assigned the Mission-1 of fixing some kind of leak in the security system at ARC. He's quite adept with computer hardware structures and is confident this will not take long. However, because Dr. DiMarco does not trust him touching the equipment, she has them running various errands for her around the hospital, elongating his stay.
Dr. Senn is in the medical stream, and thus has no missions. He genuinely cares about the patients and is the most out-of-loop of the authorities.
[JK] is the same. Though since the execution of [JL] he has not been at full functioning abilities, thus Dr. DiMarco has him joining Isaac on the wonderfully mundane, never-ending tasks that appear around ARC.
Dr. DiMarco however, is actually an Agent of the Endless with the Mission-4 of eliminating the Endless' largest threats (the patients of ARC) as well as junior agents Alice and Isaac. Hence, if her mission is a success, Alice will die and thus Agent Mei is unable to complete his Mission-3, resulting in his execution.
Dr. DiMarco is strategic. She gently plans lessons and activities and is well aware that Gale, Kepler, and Ramon are planning escape using an explosive device. The device design has been rigged to destroy the entire rehabilitation centre instead, thus completing her Mission-4.
Based on this model, I haven't quite figured out a use for the female patients (Sam, Heike, Rita, Seraphine).