The game I am in has a few greek scions: Artemis, Ares, and Athena.
The play and rules sort of evolved over time. We used aspects and compels on aspects to reflect the tidal pull of the parents on the scions.
Artemis:
Female player/character was a virgin. Hunted "evil" in the name of Artemis. Sort of an eco-feminist thing. The GM had her struggle with the sentiment/philosophy call of her mother with the vicious man-killing reality of her sisters. So she had a difficulty in discerning what was the right course of action as given by her aspects and her people. Her character did not really get interesting until the GM fleshed out a culture that forced her to make choices with tough consequences to her choices. She had a mixture of compels, betrayals, and violent scenes. Oh...and White Court Vampires trying to get into her virgin pants. Her powers were speed, incite fear after plugging the prey with an arrow, and bow skills. As she was a new player to DFRPG she decided to play a scion that was sheltered on a Med island with other Artemis scion's and constantly played up the culture clash driven by the interpretations of proper behavior by her people. She did find out that other scion's are not the best interpreters of Artemis' will. The GM would compel the scion a lot around bad male behavior. Especially the ubermale scion of Ares.
Ares
For Ares we went with a chimeric father who had sired a few thousand bastards and was uncaring of their fates. As the scions evolve they find themselves adept at one or two aspects of war. Not all scions are created alike. They had a few commonalities: strength, speed, and toughness. Ares manifested in different forms largely dictated by the greatest bloodletting/war that happened in the region (a nod to American Gods). So Ares in South Bend took the form of a genteel union/confederate general. In Europe more like a Nazi/Ruski form. All scions of Ares had a form of cassandras tears. Visions of war/conflict that draw them to conflict like a piece of meat draws flies. All scions of Ares need to perform an act of glory/fame (via Hellenic Code) to gain the notice of Ares. Then the problems really begin as Ares agenda is complex, unknowable, and generally demonizing an in awful way. To flesh it out the scions of Ares had the goal of becoming "300" an elite force of scions who do the bidding of the gods. Until the scion attained the status of being a "hero" the scion is mortal (as in can die of old age). At a certain point scions do gain a long life. Most don't as the vast majority of scions die young via war and their addition to the most dangerous trade. In one story arc scions of ares were near like roach/xenomoprh status. Hordes of deadly things that you squish in numbers before they squish you. Scions of Ares in the game were generally disliked and seen not too dissimilar than ghouls (minus cannibalism).
The scion in the party was a master of weapons ("The Use of Arms") and manifested the aspect of butchery in war(Honey Badger Don't Care). So warfare would incite a bloodlust that would clash with humane aspects of the character ("Take the Grenade"). The character was molded on Yato of Noragami. A little stray cat godling trying to swear off calamity yet being drawn back in again and again with some seriously bad social habits. To aid in this the scion had a game mechanic flaw. Whenever he used supernatural speed he would gain a mild mental consequence of bloodlust/adrenaline high that represented the peril of addiction to his heritage as he took on an inhuman form. This flaw was readily taggable to characters/monsters that play on emotions. He got taken out by a wrath oriented WCV zapping him during bloodlust and assessing "Honey Badger Don't Care". The scion had a bit of a drinking problem vis a vis PTSD/Horror at his actions ("Children's Eyes that Hate You, Broken and Mad"- Siegfried Sassoon.) As the arc continued the scion was the son that Ares would give the most morally questionable jobs. His package was Strength, Speed, Toughness, Cassandras Tears with a sort of human form and mild mental consequence when using speed (a nod to Guts from Beserk while wearing the armor of the beserker). As the arc continued the agenda of Ares was revealed: For the White Council to go to war and to rescind the first law as the scion was with a party of wizards. The Ares arc created by the scion was not the main arc of the game. It was still a reality vs outside the fae really suck story.
Athena:
That character had an interesting use of 4 pts into supernatural senses. She had the ability to see the truth in conflicts, the ability to divine the best tactical solution causing the least harm, and a sort of call on the GM for a bit of wisdom power. The scion of Ares had a grand old time ignoring the scion of Athena's input. Sadly the scion of Athena's input would more wise, humane, and generally "good." As the party was heavily influenced by a war like mindset the party did not really trust in the scion of Athena. That and the player had her as a scion of Athena and daughter of Morgan. The word "snitch" came to mind many times.
Scions of Whatever "Wiki" can be really cool additions to a game that uses aspects, compels, and GMs willing to flesh out culture pieces beyond Dresden Files. The introduction of Hades in Skin Game sure juiced the campaign. The above posters are right in that its fun to play the Call of the parent on the scion and the struggle that it creates as the agenda of the parent is inhuman. Some of example on fortune and Dionysus I am going to steal.
