Seeds get the basic nine Scion Attributes, which are divided into Physical, Mental, and Social categories. They prioritize points (8/6/4?) into Primary, Secondary, and Tertiary categories just like Scion characters. In addition, they gain a certain number of points (yet to be decided) on Mythological (read: Epic) attributes and supernatural powers; abilities directly based off Attributes (in general, powers that affect the user only) are classified as Knacks (we need to come up with another name for this), while abilities that (generally) affect others are Boons (ditto).
In place of Legend, Seeds get Mythos, which is a measure of how 'in-tune' a character is with his Seed; how much the mythological archetype within them dominates their personality and actions. Starting characters have Mythos 2, and Mythos can be bought up with bonus points or XP.
The Seed bears an unearthly resistance to most forms of harm, shrugging off wounds that would kill a normal human. In exchange, the character also has a crippling weakness to one or two means of attack. A Werewolf Seed might have a weakness to silver, and a Hydra Seed might have a weakness to fire. Add the character's Mythos to Bashing and Lethal soak when calculating damage from all attacks except for those that exploit the character's Achilles' Heel; those inflict Aggravated damage automatically, which cannot be healed through regenerative Knacks.
The Seed is effectively immune to one or more forms of environmental damage. A Rusalka or Mermaid Seed might breathe water as well as air, and a Salamander seed might sit unharmed in the hottest inferno. The character takes no damage from the environment he or she is inured to.