Fate/Zero features a collection of the best Servants that we’ve seen in the Fate series so far. Rather than focusing on their traits and parameters as Servants, their characters were fleshed out better than even that of most of the Masters. Among the seven, the servant Rider whose identity was that of Alexander the Great or Iskandar King of Conquerers was easily the best in terms of characterization.
Instantly noticeable was the unique relationship that Iskandar had with his master Waver Velvet. While the other Masters of the Fourth Holy Grail War were more well-versed in terms of handling Servants, Waver was not. Because of this, he was less overbearing and did not exactly have a clear cut strategy when compared to other Masters. This fact in itself was one of the major factors that allowed for the unique relationship between the two.
Iskandar and Waver were simply not like the traditional Master and Servant. Instead, Iskandar was seen constantly teaching Waver his own ways, explaining his own beliefs. Rather than being a follower as other servants were, Iskandar was constantly taking the lead and making decisions with regards to the Fourth Holy Grail War. In fact most of the time, Waver was left to simply tag along for the ride rather than instigating actions. For the majority of the series, Waver was going along with the whims of Iskandar.
Most of the entertainment from their relationship actually comes from the fact that their roles seem to be reversed in that sense. Rather than Waver being able to control his own servant as most masters are able to, he is often left cleaning up the mess left behind by Iskandar who does whatever he deems fit. Despite all the customs of modern day society coupled with Waver’s repeated efforts to urge Iskandar to stick to social norms, many occasions especially earlier on in Fate/Zero see Iskandar sticking to his own beliefs.
The best aspect of Iskandar’s character is that he truly embodied his beliefs. His actions throughout the series were a clear result of the beliefs that he held and explained earlier on in the series. One of the recurring ideas that Iskandar talks about is connected to his moniker of King of Conquerers. In particular, he repeatedly explains what conquering means to him. His best example is explained through his strongest Noble Phantasm, Ionian Hetaroi. He explains that each of the soldiers in his army is strong enough to be a Servant summoned by the Holy Grail. Despite their strength, they all choose to follow Iskandar as a member of his army because he conquerers without degrading the person. His brand of conquering involves showing them his own ideals and leading them as a figurehead towards a dream essentially leading by example rather than by cruelty and slavery.
This means of conquering is actually best seen through his relationship with Waver Velvet who in essence inherently holds a higher position than the King of Conquerers being the latter’s Master in the Holy Grail War. Throughout Fate/Zero, Iskandar expresses his beliefs to Waver. He initially acknowledges Waver’s weakness but chooses to ride with him anyway. As Fate/Zero progressed, Iskandar was slowly giving Waver more acknowledgement and respect, something that the latter never really had. Eventually, he claims Waver to be not only a worthy Master but also an equal. The culmination of their relationship is seen when he truly acknowledges Waver by asking him to be a part of his army. It is at this moment that we are made to realize that Iskandar had conquered Waver by earning his respect. Rather than highlighting the relationship between Master and Servant, the two displayed the relationship expected between king and subject.