The development of personae is a very important part of Kannagara. Personae get better at what they do, and gain new abilities. Sometimes, they even transform into something other than what they were.
Because this is such an important part of the game, there is an important principle that I want to respect. Any persona, at any point, can work towards becoming anything that the game makes available as a possibility to any persona. The change might not be possible immediately, and might be difficult, but it is always possible. Furthermore, this possibility is part of the standard game; it does not need a special exception of any kind.
Most existing games break this requirement. Ars Magica, for example, provides no standard way for a character with no ability to work magic to get The Gift. Similarly, a character who starts off as a faerie cannot become human. The reverse is possible, but far from easy. In Pathfinder, a character cannot easily change race. Even changing between classes is difficult, as the first level of a new class counts as a higher level, and the new rules for retraining, which recognise the appeal of this requirement, are outside the normal methods of advancement — retraining takes time, not experience points.
Of course, it makes perfectly good sense to break this requirement. If you have fantasy races, it makes sense that characters will not be able to change their race. Real people can’t do that, after all. That means that Kannagara will be a little artificial. Fortunately, I have supernatural powers available, and those will allow personae to make the necessary changes. Sex changes will be possible, but so will more important changes: humans can become kitsune, kitsune can become kami, and so on. Further, no change is irreversible.
That does not mean that all changes will be equally appealing to all personae. Some changes will build naturally on each other, so that once a persona starts down a path, continuing down that path will seem like a better use of time and effort. Similarly, it may not be possible for a persona to be a particular combination of possibilities at the same time. Kitsune are an obvious example. A kitsune is a fox who can take human form, so it is not possible to be a kitsune and a human at the same time.
New persona options will be introduced along with the ways in which personae can discover that they are possible. In that way, players will never feel that their personae would have made a different decision in the past. A player might wish that her persona had known about a certain possibility earlier, as might the persona, but it will never be the case that the persona did know about that possibility even though the player did not, and it will also never be the case that the possibility is no longer open to the persona.
There is a second important principle. Development should be part of play. That does not necessarily mean that the group will play out all parts of development, although they will do so for some. It does mean that development will not be abstracted, and that personae and players will make the same sort of decisions. Development in Ars Magica does follow this principle; characters make the same developmental choices as players, deciding what to study or research in a given season. Pathfinder does not; the details of development are abstracted. Kannagara will be closer to Ars Magica, but with even more emphasis on playing out character development.