Each adventure in the G trilogy would thus feature a stronger set of giant foemen so that the difficulty of the sequential adventures could increase over time. As we know, Gary had already conceived the giants of Dungeons & Dragons (in 1972-1974) as being represented by five sub-species, from weakest to strongest: the hill, stone, frost, fire, and cloud giants. Storm giants were added a bit later. Of those sub-races, stone giants are neutral, storm giants are good, and cloud giants can be either good or evil,  so the three ascending tiers of purely evil giant foemen are therefore hill, frost, and fire. These were (not coincidentally) the very races of the antagonists which had been featured, alongside trolls, in The Roaring Trumpet too. Considering this and the precepts of the already-published Monster Manual (1977), it seemed to Gary that hints in the hill giant stronghold should lead to the lair of the frost giants, and the frost giant domain’s revelations should in turn lead to the fortress of the fire giants and their loathsome troll-servants. In this way the three G modules would progress in level of challenge from fairly hard to insanely hard. (This by the way would make the G scenarios perfectly suited to frame tournament rounds in competitive D&D, and that is exactly how they were first put to use.)
This shrewd design choice, however, presented another quandary. The brutish hill giants of The Roaring Trumpet are colorfully represented, but the details are sparse, and Norse mythology is not much help either. They are for example fleetingly mentioned eight times in the 1916 English translation of Snorri Sturulson’s Prose Edda, but compared to the well-represented frost and fire giants, their lore is lacking at best.  We learn very little from such sources of the hill giants’ unique characteristics, their beliefs, or their origins, destiny, or leadership. Gary would therefore need to find other resonant sources in legendry to assist him in fleshing out the Steading’s hill giants as evocative and fearsome foes with a culture all their own.
One of Gary’s inspirations may have been the story of the crafty Ysbaddaden Bencawr, chief of giants. Ysbaddaden is, to point out some intriguing parallels, a bolt-hurling murderer and torturer who resides in a great hall within a castle which is protected by ferocious guard hounds (much like the dire wolves found in Steading). These details are found in various tellings of the Welsh myth of Culhwch and Olwen.  But despite this parallel, the most obvious folkloric sources Gary employed in devising G1 are The History of Jack and the Giants (text by J. White, 1711, from unknown tales earlier) and its later and more widely-known derivative successor: Jack the Giant Killer, as featured in English Fairy Tales, by Joseph Jacobs (1890). From what we know of Gary’s youthful proclivities, it seems likely that he may have first learned of these particular stories as a child via Andrew Lang’s Blue Fairy Book.
Today, most people know only the dim fable of Jack and the Beanstalk (itself being the source for Gary’s conception of the cloud giants in D&D). However, Jack in his early stories faced and defeated many other earth-based giants, including Cormoran, Blunderbore, Rebecks, Thunderdel, Galligantus, and a two-headed Welsh giant (technically an “ettin” in AD&D terms). These stories of Jack the fighting man collectively tell us that English earthbound giants are dim yet cunning, brutish, violent, greedy, and hateful toward mankind. They are frequently armed with tree-trunk clubs. Indeed, one of the giants who threatens Jack chants grimly, “Though here you lodge with me this night, you shall not see the morning light; my club shall dash your brains out quite!” 
We learn a bit more of hill giant depravity (and their utter lack of humor) in The Roaring Trumpet, when Loki tells Harold Shea that when a warlock named Birger tricked a hill giant into marrying a goat (through polymorph or illusion, perhaps?), the enraged giant “cut Birger open, tied one end of his entrails to a tree, and chased him around it. Hee hee!” 
Gary certainly borrowed much from such sources, but he added a great deal more original content to make the Steading scenario all his own. When we look beyond the centuries-old inspirational tales, we can learn a great deal more from a close reading of Gary’s module. There is a wealth of information crammed into Steading’s eight pages, and some of the secrets are merely insinuated (to be elaborated upon in later products, and through Gary’s later discussions with many D&D fans online).
But what are these secrets, exactly? How can they benefit a Dungeon Master, or a scenario designer for Fantasy Role-Playing Games?
Hereafter we will take a detailed look at Gary’s cunning trove of “giant” secrets. I believe that you, the reader, will find a considerable amount of material here which will encourage and inspire mythic quirks in your own further adventures … no matter which game you choose to master.
One day the god Thor, with his servant Thialfi, and accompanied by Loki, set out on a journey to the giant’s country. … When night came on they found themselves in an immense forest … and at last came to a very large hall, with an entrance that took the whole breadth of one end of the building.
— The Age of Fable: Stories of Gods and Heroes, by Thomas Bulfinch, 1855.
The Steading is a foreboding and exciting place. A considerable amount of G1’s inspirational appeal lies not only in its setting and atmosphere, but also in its evocative illustrations. The first illustration, of course, is the image which was designed to hook sales: an action-filled cover piece by David C. Sutherland III. The cover features a great battle between nigh-overwhelmed adventurers and a hill giant. An average hill giant is lean and only a little over 10’ tall,  so this mighty potbellied specimen may well be the chieftain Nosnra himself. The depicted giant has been surprised by the party it seems, because he has had time to pick up his sword but not yet his stretched-hide shield. One greave has been hastily fastened to his shin, but the other lies unattended on the floor. Two beleaguered fighting men engage this mighty foe, who in turn is interrupting a magic-user’s spell by spilling wine over his head. Meanwhile, a crafty mustachioed thief moves quickly into position for a backstabbing attack before the battle can turn into an outright disaster.
The illustrated giants in G1 (crafted by both Sutherland and David Trampier) are true to de Campe’s and Pratt’s 1940 description: the “hills” are basically oversized Neanderthals, being stooped, hairy, muscular, howling and scratching, with beetle brows and jutting lower jaws.  These hill giants are led by a fearsome chieftain who goes by the name of Nosnra. At first glance, this seems like nothing more than an exotic Gygaxian turn of phrase which makes an excellent name for a boorish chief. However, sharp-eyed D&D players have long known that turning Nosnra’s name around (to “Arn[e]son”) reveals that Gary was actually taking a moment to aim a deliberate jibe at the co-designer of the original Dungeons & Dragons game. (Gary and Arneson had a very unfortunate falling out, as they say, with justifiable hard feelings on both sides; but that is a tale for another day.)
The character Nosnra is not only a nod to Arneson, however. As Jon Peterson has pointed out in Playing at the World,  Gary’s hill giant chief is also a slight portrayal of Utgardaloki, as featured in The Roaring Trumpet. Utgardaloki, however, is a cunning rogue (and perhaps a dabbler in illusions) while Nosnra is basically just an overgrown barbarian. Nosnra is indeed a cunning bully who is smarter than his many tribe-folk, but he is no magician and is secretly overmatched and controlled by far more intelligent villains who lurk in the shadows: the drow-folk of Lady Eclavdra and House Eilservs. 
FOOTNOTES TO PART II
 The giants’ alignments were simpler as first conceived for original D&D, but they became more nuanced and complex with the publication of AD&D. Refer to the AD&D Monster Manual (1977), pp. 44-45.
 For the specific mentions of hill giants, refer to the index of The Prose Edda by Snorri Sturluson, Translated from the Icelandic, with an Introduction by Arthur Gilchrist Brodeur, Ph.D. (1916). This volume is available online.
 Refer for example to Kilhwch and Olwen, or The Twrch Trwyth, as translated by Lady Charlotte Guest (1877) and similar versions.
 This charming quote is derived from the Blue Fairy Book version of The History of Jack the Giant Killer.
 The Roaring Trumpet, by L. Sprague de Camp and Fletcher Pratt, Chapter Four.
 Refer to the Monster Manual (1977), pg. 45.
 The Roaring Trumpet, Chapter Six.
 Refer to Playing at the World, by Jon Peterson, pg. 151.
 The plots and machinations of Eclavdra and House Eilservs are elaborated upon in Dungeon Module D3, Vault of the Drow, by E. Gary Gygax, pg. 18.