Constructs, Undead, and Souls

Constructs and undead, while commonly souless shells with no cognitive understanding outside of feral hunger and programmed algorithms have been known to develop sentient consciousnesses and even show signs of possessing a soul. Currently, there are several known ways of how this occurs.
Higher undead such as werewolves, vampires, or revenant are created when the living body of a creature is twisted into an undead nightmare around the still intact soul of the creature. This means that they never loose their soul to begin with, and as such, never loose sight of their sentience. Lesser undead such as zombies, skeletons, and drugar on the other hand are born from already slain corpses, and as such, have no soul. Intensive research on zombies show that when first resurrected, a zombie's will is bound to the one who raised it, however this alliance quickly fades and the zombie becomes a rabid feral creature, attacking and attempting to devour anything that moves within its line of sight. A talented scientist or mage can continue to expend source in order to maintain control over the zombie, but while in this state, the zombie remains a mindless thrall. Left uncontrolled for a period averaging about 3 weeks, changes are noted within the zombie. They often grow less feral, and begin responding negatively to things like pain, heat, or cold and positively to things like music, or being spoken to. This gradual change continues over the course of another 2 weeks where on average the zombie begins to remember its life before it died and begins vocalizing again. At this time the zombie's coordination begins making a marked improvement and the improvement can be sped up through physical therapy. Furthermore, the bloodlust seems to die away, only leaving a taste for raw meat rather than an all consuming need to devour it. Within another few weeks, the zombie appears to have regained all of its faculties and has all the memories it had in life, although its personality is often radically different than the one it had in life. It is theorized that by creating a zombie, the necromancer or other such person, uses magic to create a seed of an artificial soul, which when left alone, draws in additional magic to grow, eventually allowing for the zombie to once again take on sentience. Skeletons however, no matter how long scientists have waited, never seem to regain any semblance to cognitive thought. It is hypothesized this is due to a skeleton's lack of biological components with which to hold rational thoughts. Lastly, Drugar are created when corpses are exposed to too much necrotic energy over a period of months to years. Drugar are drawn to the souls of the living, and will devour the living in order to gain small pieces of souls, the more souls a drugar consumes the more lifelike they become, however they never seem to be able to shake the constant hunger for more souls.
Constructs on the other hand seem to operate under a different set of rules. First, the construct must be constructed in such a way where it is capable of complex problem solving. This often means they must have crystal lattice processor cores. Provided they can perform complex processing and problem solving, it is usually only a matter of time before the construct begins to question its existence and shortly after that they often gain the ability to ignore their programming and become independent fully functioning sentient machines. The exact reasons for this is unknown. Given an awakened construct's sudden susceptibility to necrotic magics and healing magic, leads credence to the idea that they have developed an actual functioning soul, but the reason why is still unknown. Some believe it may have to do with the similarity between the crystal lattice cores being similar to the make of of the Illustrious, while others believe it may have been a deal between Rain, the creator of the first constructs, and Atlus, the master of souls that result in some constructs being able to obtain a soul. But it is currently unknown.