The Neutral Zone

Question: I have not read all your adventures yet, but have any of the players had to deal with a major antagonist that was neither linked to Titans nor any God?

Hero-level Scions have dealt with mortal antagonists! Sangria, who was an internationally-wanted terrorist at the beginning of her career, lived with the need to constantly fight or avoid local police and eventually local military forces, which in large enough numbers were seriously dangerous to both her and her companions; once, a shell took her oldest son's arm off (he got better, but it was serious business). Padma in the Eastern Promises game has a serious antagonistic relationship with her mortal former governess, who has been attempting to ruin her reputation and now, after Padma got her fired, wants to ruin or end her life as well. Mohini's mentor, Shweta, recently attempted to have her barred from the temple out of a combination of outraged sensibilities and professional jealousy. Many Fatebound mortals have also been antagonistic figures against Scions, including Dylan Dion, who wanted to kill off Geoff, Christopher Chance, who kept laying mines for Goze to stumble into around the house and Bobby Pabst, whose determination to herald Seamus' every movement nearly killed him several times.

But, of course, Scions outstrip mortals (even Fatebound ones) so quickly that they really can't be challenged by them anymore after Legend 4 or so, which means that they need Legendary creatures like themselves to really be effective antagonists (or mortals that are enhanced by Legendary enemies, which is really the same thing, just by proxy). And the majority of the time, that's going to mean creatures that are either aligned with the Titans or the gods, which are the two major supernatural forces in the world of Scion. There are tons of both running around - Titanspawn, Scions, mortals who have been enhanced by gods or Titans, and so on, and they make up the bulk of creatures magical enough to really cause a Scion any problems.

The only other option is for them to go up against an unaligned lesser immortal or magical race, which certainly can happen but isn't as common since there are far fewer of these creatures around that don't have connections to the gods or Titans, both of whom are actively recruiting as much magical firepower to fight one another as they can muster. We have had antagonists from those groups as well, though; the most obvious are the fairy courts, which were not officially aligned with any of the gods or Titans but still made up a considerable chapter in the problems and adventures of the Skeins of Fate group. Unaligned Nemean and Typhonian beasts could also be theoretically neutral antagonists, but it's even more rare that you'll have any of those running around that weren't originally created by either a god or a Titan.

Even lesser immortals, though, will stop being really useful antagonists once your Scions have become gods; by definition, they just can't match up to their power level, so they'll either need to antagonize the Scions in large forces, give up or be trounced. Once Scions have become gods, the only enemies who really threaten them are those who are of a like potency, and that means other gods and the Titans themselves. Just like the gods of mythology, their foes are as cosmically powerful as themselves; once they've reached that pinnacle, there's no alternative but for them to fight one another or the Titans, because those are the only beings left that can be true challenges to them. Our god-level Scions have fellow Scions-turned-divine like Maquicelotl as their antagonists, or gods like Stribog or Tezcatlipoca that work against them, or Titan Avatars like Itzpapalotl or Utgarde-Loki who threaten them. Lesser immortals are no longer a problem for them, and the days when mortals could interfere in their doings are but a distant dream.

Unless you consider that Fatebound mortals who hate them can still affect them through negative Fatebonds, so that's a way that they're still antagonized, and rather permanently, too, since it's nearly impossible to get rid of maximum-level Fatebonds. The mortal menace lives on!