Hello! Mai here,
As there had been a lot of speculation of the difference between a spirit whisperer and an exorcist, especially with my friends who had been reading Flower and Vase, I would like to clarify that they do have specific roles based on their ancestral origin. And so, I had my friends ask me a bunch of questions of which I think will also help my other readers understand the differences between the two. I don't know if this helps but I will try my best.
1.) Are spirit whisperers and exorcists the same? If no, what makes them different?
No, they are not the same. Their difference roots from whence they originated from. Allow me to begin from 1000 years ago then to the great war that had happened 400 years ago FAV timeline.
1000 years ago was the time when humans were all equal and close to their creator. As humans were able to communicate with their God directly, they were also able to communicate with all creation as it is apparent that all created by their maker has life, and whichever has life has a spirit. Everyone was one and the same living in harmony. Basically, all of the first generations were the original spirit whisperers. Exorcists were not established before as there had been no need for such. Priests in each community served as celestial guides to every chief of a tribe and there so.
Fast forward to the great war FAV time 400 years ago was the beginning of the next generation of humans to inhabit the earth. All ties to their God were cut off due to their abuse and hunger for power. The Paladin arrives and closes off all of their gifts (sixth sense) which made them the neo-generation of mortals to inhabit the earth that would only rely on their own strengths and no more of the spiritual intervention unlike before where all spirits roaming the earth were able to communicate with them.
However, as the Paladin was also mortal, he committed a grave mistake by not foreseeing what will happen to the future generation if none of the current inhabitants will be able to help maintain the balance of the malicious and good especially with all the unclosed dents that had already been a problem for centuries past. With the breaking of the Paladin's spirit into three came forth the new generation of spirit whisperers who were death's servants, being the only ones able to maintain direct contact with the supernatural and have the gift of the first generation. They were Dominic, Remus, and Minos.
But as their abilities grow stronger without the power to purify as descendants of the dark, the remaining priests of the neo-generation who had no ability to sense spirits offered up their sons to the gods as a purification ritual that they become beacons of light for the servants of death. Thus came forth the first batch of exorcists who worked side by side with Dominic, Remus, and Minos as they search for all malicious spirits and the dents they came from.
That was the beginning of the secret society of spiritual peacemakers, the DoReMi.
In simpler terms:
Spirit Whisperers- servants of death
Exorcists- instruments of the gods
2.) What makes the Messiahs different then? Haven't they all seen death at some point?
I can't spill much of the details on the real purpose of the Messiahs as they hold a deeper and darker secret for the society (HAHAHA). But I can affirm that yes they have all seen death which made them a qualifying member of Messiah. However, like what I said, the functions are all the same. Spirit Whisperers and Exorcists need to work together for it to be a successful process when it comes to missions.
3.) How are the pairs chosen? Like who gets to choose?
They are usually paired based on their wavelength (as what Olivia explained on Prim's orientation with Vin in her office). Upon recruitment, their data is sent to the "Union of Overseers" or the UNOS, which includes all the presidents of all the different branches all over the Pacific Rim and they discuss the potentiality of each candidate.
4.) If only Exorcists are able to purify [or make seals], how is it that Prim was able to do the protective sutra on the latest training she had with Sig at the cemetery?
No comment.
[added question just now]
5.) Okay if you're not answering that, how exactly does one know whether he or she is an exorcist or a spirit whisperer respectively? Since it is somehow depicted in the story that exorcists share some qualities of a spirit whisperer.
For that point my friend you are correct. I guess we can all agree that this might be an issue in the breeding process, but I'll make this is an exception to explain (although it may come off as a spoiler).
To put it in simpler terms, for the years that the secret society of spirit whisperers and exorcists existed, there has also been controlling in the selection for marriage. Most exorcists that want to marry are being paired to families with good spiritual lineage, not necessarily a spirit whisperer but preferably of the same exorcist group. It is against DoReMi laws for whisperers and exorcists to copulate with those who do not have the gift. Whisperers and Exorcists were discouraged to get married as it would create an outlier in the population, but after that pandemic 200 years ago, there has been no choice but to debunk that "discouraging" factor as it would seem to be most beneficial for those of the same line of work to just get along and raise a family. The reason why it is discouraged, it is because, children whose parents are whisperer and exorcist rarely survive as their source of mana would be in conflict within them. They may survive at birth but they won't get past the age of three (however this information might be outdated and there was no clear evidence to such). So most of the modern families right now in DoReMi society are either purebred or no children at all.
For that last statement that exorcists share the same qualities of a whisperer, only with the part that they CAN sense spirits and the like same with the whisperers. But then they are stuck with only an idea of the presence through mana tracing unless they resonate with their paired whisperer to fully grasp the situation. Exorcists are after all trained with years of total concentration to be able to heighten their senses to be able to be at par with the senses of a spirit whisperer. As opposed to whisperers whose senses are all over the place because they don't need to think about full concentration before they can sense something. With such chaotic energy, an exorcist will have to keep the whisperer on a check as to not carelessly setting free malicious spirits unconsciously. But through the serious efforts of DoReMi in training their whisperers, most of their recruits have learned how to keep in their extreme spiritual energy. But as for Prim, she's beyond control, as such the scientists of DoReMi tailored a limiter for her, the headphones that she's been wearing day and night.