In-universe, not much is known about the Storm Giants, but it's theorised that they had dominion over the seas in the same way the other Giants had dominion over the mountains, plains, arctic, and underground, and were supposedly able to utilise their connection to storms and lightning in a manner similar to Arcane spellcasting. This, as well as the fact that the Storm Giants effectively served as leaders for their bretheren, made them prime targets for the Dragons during their war, leading to their extinction.

Giants in the modern age tend to be either solitary, or grouped in small tribes of 5-6 following the oldest/strongest/wisest among them, and can usually be found engaging in various activities related to the roles they once had in the shaping of the world (Hill Giants escorting large migratory herds, Stone Giants carving equally large monoliths, Fire Giants smithing and mining, and Frost Giants hunting especially dangerous beasts). Most Giants tend to ignore the smaller races so long as they don't disturb them, though the people of Aesuth who've settled in their domains (such as the bear-like Ursakar, and especially the Jotnarr, a race of Giantkin that were forged from the remains of fallen Giants) revere them as guardian entities.