Nero's Profile
An orphan that was adopted by the Order of the Sword, he has grown up to be a Holy Knight in the Order in the city of Fortuna. Nero is a descendant of Sparda’s blood – although it is not yet known if he is a direct relation to Dante and Vergil - hence his right arm and the powers of the “Devil Bringer.” He tends to not get along well with others and prefers to work alone, so he is usually given the Order's "special assignments".
From this we know one thing about Nero. He was an orphan raised by the Order of the Sword. Was he taken simply because they needed soldiers or did they know something/expect something about him? Nero is similar to Dante and Vergil in the general trait that they like to work alone. Dante was working alone in Devil May Cry 3, until he met Lady. Vergil was not working alone, but it seemed he needed to use Arkham (So it was simply a case of using him for his own personal gain) it had nothing to do with wanting to work with him. However, out of the two who would more than likely prefer to work alone would be Vergil. The Order must of adopted him for other means, as how would Sanctus know so much about Nero? We know one of the Order's key goals was to learn more about 'demons' and the way in which they work. The idea that Nero was a 'test subject' is not an impossible one. We know that the Order were conducting experiments all the time. Perhaps they were trying to craft a great warrior? Nero may of been the subject all along. A secret project worked on by Sanctus. It's not so far fetched as it may sound. The Order had already recovered Yamato, which was a significant recovery in itself. Because the last time Yamato was seen was on Mallet Island, when Dante 'defeated' (Not killed, it was never stated that way) Vergil. And we all know that Mallet Island collapsed in on itself after Mundus was sent back to the Underworld by Dante. So how did the Order gain Yamato?
It's true that colours play a part in a character's design. They hold some minor signifance. Dante wears mainly red, Vergil wears blue and Sparda wore purple. As for Nero -
'He wears a red zip-up hoodie underneath his coat, and a navy blue muscle-shirt beneath that'. Strange, Nero seems to wear all three colours. He wears something purple, red and blue. What is the means to wear all these three colours? What are Capcom hinting at? That Nero is all three roled into one?
Also I keep seeing this main point made regarding Nero. The point is, he is a 'descendant' of Sparda's blood'. However, the word descendant actually doesn't mean what we're associating for Nero's case. How are we to know which meaning Capcom were using when Sanctus stated Nero was a descendant?
Define Descendant
1. A person, animal, or plant whose descent can be traced to a particular individual or group.
2. Something derived from a prototype or earlier form: Today's bicycles are descendants of the earlier velocipede.
3. In astrology, the point of the ecliptic or the sign of the zodiac that sets in the west at the time of a person's birth or other event.
Define Descendent
1. Moving downward; descending.
2. Proceeding by descent from an ancestor.
In current English, however, descendant usually covers descendent‘s territory as well as its own. In fact, correct use of descendent according to its conventional sense is so rare that we should probably consider it a dead word. It may have been useful in the past, but people apparently don’t find it useful today.
Sorry for the history lessons on these words. But we have to understand which way of using these words they were going for in this sense. Otherwise we could look into other understandings of Nero's character.
If Nero is a 'descendant' in the sense that he is derived from a prototype or an earlier form, that means he received his powers via a previous source. Considering the great likeness surounding Nero and Vergil, I would assume this could mean that Nero is a 'descendant' in the terms that he recieved his powers from a source relating to Vergil. If so I would deduce that Nero was not born with these physical traits (The blue eyes and the white hair). I would assume that those traits were 'inherited' from that source mentioned. When he received this power from the 'source' he underwent a physical change of appearance in terms that he gained his demonic look. Sanctus may state that Nero is a 'descendant' of Sparda. But Vergil is Sparda's son, therefore holds Sparda's blood and power. If Nero was a 'descendant' in terms that he 'inherited' his powers via means of a source relating to Vergil, that would in conclusion mean the same thing. That does not have to mean that Nero is directly a part of Sparda's family or that he had to be born with his blood. The word inherited has different meanings. We can't just look at one meaning for that word. If we observe other meanings, what I'm saying can be said to be possibly true also.
Define Inherited
1. To gain (something) as one's right or portion. To receive (property or a title, for example) from an ancestor by legal succession or will.
2. To receive by bequest or as a legacy.
3. To receive or take over from a predecessor.
4. To receive (a characteristic) from one's parents by genetic transmission.
Sanctus could of been claiming that Nero truly has 'inherited' (As in it's his right to receive) Sparda's power. That does not necessarily mean it had to be handed down to him through birth of by legacy.
This is also a likely possibility that Nero could of changed from human to demon considering the valid points that humans have altered themselves into demons before (Or humans with such physical appearances and powers) of demons. Examples are Sanctus himself and Arius in Devil May Cry 2. Therefore, Nero being another human turned demon is not an impossible theory.
Nero's connection to Yamato could only be due to the fact that his original source of power came from Vergil. Ultimately then we could assume that Nero may not have a Devil Trigger, because he in fact is not a devil. If Nero were born human and altered by any form of experiment, we do not know the exact extent of such a thing. To me though logically, I feel that this could be a reason as to why he has no Devil Trigger. The Devil Bringer could of been a result of the experiment going wrong in terms of the physical alteration. However, it could of been the result of it going right (Enhancing his human form to a more demonic form) Why else does Nero have an arm that looks demonic and holds demonic power at all times, whereas Dante's arm only looks human in appearance? Perhaps this change has not spread throughout Nero's body yet, and he will in turn alter into a full demon (Perhaps by too much power input into him or because he is trying to control something that is beyond his control). When Arkham tried to control Sparda's power it rejected him because he was too weak and it altered him into a demonic blob (Clearly not meant to represent Sparda's true power or form). The point being, it essentially backfired on him. We don't even know what Nero could be changing into. It could be a possitive or a negative outcome, really.
These are just some ideas I am throwing around from what I have read and came to judge for myself. As interesting as every idea seems to be, the one thing that seems to logically fit for me and make any form of sense would be Nero belonging to the Order of the Sword out of means of experimentation.