The eldest of the Ulyssean Triumvirate, Servius Decimus is the literal embodiment of the emotions which coursed through Ulysses' being. Due to a single glitch within the Apple of Eden upon his creation, Servius' processing becomes much more prone to the powerful emotions such as those of hatred and anger.
Servius resembles a typical Armada musketeer, minus that he is built to appear (and to be) a clockwork officer often seen in Marleybone as well as having a somewhat harsher look-
Dressed in a midnight black officer's uniform with golden fringe, with white accents. His boots are fine black leather with golden trimming, much like Ulysses' when he reached the rank of Armada Admiral. The golden corona often found on the elites and officers is also present on Servius, though with one extra addition, which is a bloody red gem set between his eyes, close to the sculpted eyebrows: allowing it to be easily concealed under his officer's capello.
Over his uniform, Servius often wears a golden colored chestplate, bearing the mark of the Valencian Imperial Armada. His primary weapon is a sleek black Armada sniper rifle (with a scope addition), decorated with golden and silver etched designs upon it, though with a few extra additions added on by Ulysses, such as a razor sharp bayonet.
A belt that went from his right shoulder down to his left side, winding around his waist bears his secondary weapon, a single, foot - long dagger that he used as his last resort weapon.
As a representative of Ulysses' emotions, Servius is particularly prone to feeling the emotion of bloodlust due to a slight glitch in the programming when Ulysses was writing it with the Apple of Eden. Once possessed by bloodlust, it becomes difficult for even Servius himself to rein it in, as shown in the instance where he all but tore apart a Templar soldier in his attempt to pry the information out of him (chapter 20 of "Valencian Legend").
However, he is also extraordinarily intiutive, able to read what others usually attempt to keep hidden from him, as shown that he had been able to pick up the changes in his creator Ulysses when the latter begun to descend into madness when others could not see it. Most of the times, Servius usually keeps to himself about those observations the way a human would keep notes, though there are also times when he speaks out about them (take for example when Ulysses is starting to lose his sanity).
It should also be noted that, due to his ability to perceive human emotions, it also contributes to a large amount of worry (as if he himself doesn't already have a mountain of other things to worry about) he harbors for his creator Ulysses, as he recognizes the possible consequences if his Commander's sanity actually snaps. Such worry more often than not also leads him to slightly fear his creator, even more so when he witnesses just what kind of destruction Ulysses is capable of when he actually loses control of himself even if it was just for short periods of time.
Also due to this capability of his, Servius often has very little logic in his actions if his emotions were to ever overpower them, leading up to the need for his twin Albinus to back him up in battle, as Albinus makes up for Servius' lack of logic (and Servius in turn for Albinus' physical weakness). Though if his emotions do not cloud his process of thinking, Servius becomes a cold, efficient soldier in battle, as his bloodlust also permits him to see all of the most painful areas he could strike at to painfully kill an opponent.
Loyal to his creator Ulysses to a fault, Servius' loyalty extends to his "siblings".
Servius was never explicitly named within Valencian Legends until chapter 18, though Ulysses could be seen working on putting him together in chapter 12, as per the demands of the Apple of Eden when it begun whispering into his mind with the blueprints that would become Servius.
It is unknown when the whispers begun, though it could be speculated that they had persisted for a while before Ulysses gave in to their demands and begun creating the elite sniper, putting him together piece by piece in a secret room located under the deck of his ship the Interceptor. Ulysses is estimated to have completed him near somewhere between chapter 17 and 18 of Valencian Legend, so Servius could not have witnessed any of the happenings in Cool Ranch and certainly not when Ulysses tormented the witchdoctor Cyrus Chamberlain, though it is certain that he knew of Septimus before his sanity started to slip.
However, what Servius had witnessed when Ulysses begun creating the second of the Ulyssean Triumvirate Quintia Presidos and what happened during the Marleybone - Valencia war, had been plenty enough for him to know the difference between his Creator's sane and insane sides.
He had accompanied Ulysses, along with the marine Captain Sentus Optimus (who had served as his combat counterpart then) to the war between Valencia and Marleybone. And he had been a part of the group to witness the attempted sabotage of the Beachhead battlestation by the Skull Island swashbuckler Adrian Devereaux, after following his Commander through the bloodstained battlefields of the Isle of Fetch.