Welcome to a new feature on the blog: the character study! I'll use this feature periodically to cover characters of note (to me, anyway) in anime/manga and - possibly - to address the complexities of their characterization and their roles within their respective series. If you have any characters you'd like to nominate, drop me a line here! In the meantime, how about some Gilgamesh?
In fandom, the two most frequents interpretations of Gilgamesh's character run thusly:
1) Gilgamesh is an arrogant douchebag.
2) Gilgamesh is an arrogant douchebag with a hidden heart full of warm and fuzzy feelings.
I find both of these interpretations problematic, honestly, though aspects of both of them might, to a certain degree, prove true. Ultimately I think Gilgamesh is a more complex and nuanced character than either of these interpretations would allow. I hope to address that here (and please be forewarned I'll generally focus my thoughts on Fate/Zero since that's the currently-running series, though I'll reference other works periodically).
Let's tackle Gilgamesh's arrogance first, because it's integral to who he is. Yes, Gilgamesh is arrogant. Undoubtedly. But I think it's important to realize that in Gilgamesh's view, he isn't being arrogant; from his perspective he's simply stating facts. He's not saying the world is his garden and he owns everything in it to make people angry - he's saying it because he believes it's true. He views challengers as usurpers because he believes he is, by right, the absolute king of all things. Moreover, though he's not invincible, he's hardly a pushover in battle. Gilgamesh has the treasury and the abilities to back up a lot of his statements; what other people perceive as arrogance I think you can also interpret as complete self-assurance and pride.
Admittedly, there are those who find even self-assurance and pride unappealing, but in the Fate universe those traits count. A lot. During the mad feast of kings and the discussions between Rider and Gilgamesh, it becomes evident that these ancient kings perceive pride as a prerequisite to kingship, an integral part of the title. To have no pride (or arrogance, if you want to call it that) is to make yourself common, unworthy of leadership. Both Rider and Gilgamesh implicitly acknowledge that kingship demands a larger-than-life figure, a godlike persona that can rule fearlessly, that (for Rider) inspires others to dream. The duty of a king is not just to lead his people, but to inspire them and push them to greater things, and that idea abjures to a degree the "king-as-a-common-man" motif.
As for Gilgamesh's warm-and-fuzzy feelings, or the lack thereof... Certainly Gilgamesh is capable of feeling. I think people often misinterpret him as being incapable of any emotion but disdain, which is inaccurate. He's bemused by Kirei, he demonstrates respect for Rider and Waver, he shows an interest in Saber, and acknowledging these things is good. However, I think the depth of Gilgamesh's feeling runs the risk of being both simultaneously over- and underestimated, so it's important to talk about what Gilgamesh feels, and why, and where it all comes from.
In the Fate/Zero universe in particular, Gilgamesh's two most significant relationships (setting aside Enkidu for a moment - I'll get there) are with Kirei and with Saber. For most of the Fate/Zero series he's the serpent twined around Kirei's neck, seducing him into darkness, and later he becomes Kirei's partner in crime; his interest in Saber leads him to focus on her in particular beyond many of the other servants and masters. His interest in both characters stems from a sort of curiosity: Gilgamesh wants to see what Kirei will do with that black, empty heart of his once he discovers desire, and in Fate/Zero particularly he wants to see how Saber will bear or collapse beneath the weight of her idealistic aspirations. In both cases, I think it's fair to say that Gil holds a fondness for both characters, and in particular takes a delight in Kirei whom he has essentially nurtured into darkness. However, his curiosity about Saber and Kirei stems not just from warm-and-lovey feelings for them, but rather from the primary source of all Gilgamesh's feeling: his relationship with Enkidu.
As a being of partially-divine origin, Gilgamesh stands alone and above most mere men. It's Enkidu who aspires to stand alongside him, Enkidu whose dreams are bigger than his reach. In Enkidu Gilgamesh finds a true companion - the only companion he will acknowledge or whose company he desires - and Enkidu still inhabits Gilgamesh's memories, his thoughts and feelings, even his Noble Phantasm. I believe that Gilgamesh's interest in and curiosity about Kirei and Saber - the fact that he's drawn to those who attempt to move beyond themselves, even when that reach seems futile or dangerous - stems from his first and most precious friendship. What Gilgamesh seems to admire most in others, or to respond to at least, is aspiration, the willingness of a person to reach beyond themselves even at great cost. (Think about this in regards to his relationship with Tokiomi, whom he obviously disdains, precisely for his lack of such traits). Though Gilgamesh believes that Saber's lofty ideals will crush her and presumes that Kirei's might render Kirei a fuller man, in both cases he responds to what defined his relationship with Enkidu. And he makes no bones about the fact that it's Enkidu he holds in highest regard, whatever he might feel about others. So does Gilgamesh have a heart? Yes. Absolutely, and for Enkidu in particular. But he won't allow that heart to become his weakness, and he won't let any relationship replace the one he holds in highest esteem.
Certainly, Gilgamesh can be infuriating. He's dismissive and whimsical, sometimes cruel, and has a tendency to disregard everything he perceives as beneath his interest. Yet in sharp contrast to other characters, he seems well-suited to deny the corrupt Grail precisely because he believes himself beyond such petty desires; his belief in his absolute sovereignty over all things inoculates him against corruption. And in the morally ambiguous world of Fate/Zero, it's not impossible for him to be so complex or for his characterization to make such demands on the viewer. A creature of contradictions, he seems well-suited to the role of antagonist in the series (alongside Kirei) - and yet it's impossible to wholly dismiss him as such.