It's not in the rules yet, however, it's going to be added soon.
After some thought, I wanted to 'organize' a potential thing that might occur with some characters in the future.
On Characters Learning New Abilities
1. They cannot learn them within days. It's an insult to everyone who has a similar ability. Say if you're learning how to fight with a lance and you've never done it before - you aren't going to be good at it until at least a year of practicing hard, and that's pushing it (you aren't going to be a 'master' until much, much longer). The same goes with learning magic - characters should NOT be able to learn magic well and easily if it's not their usual thing.
Also, characters who come into the game with an ability will, with some exceptions, almost always be more powerful than people who learn a trait within the CU realm. If Alice learns to shoot a gun, she's not going to be as good at it as Sal, without serious...plot reasons that slowly develop over a long period of time, but that's unlikely.
2. Learning an ability doesn't mean you can use it well and easily immediately! That's not what learning is.
3. This is being put out there because new talents and pursuits need to be kept in check so we don't have tons of characters turning into Superman or That Dude Who Can Take Care Of Everything Alone. That's boring.
While it might be fun or necessary, or inevitable due to the storyline, characters should be encouraged to learn how to use the techniques they have instead of learning everything else.
Also! While characters MIGHT learn magic or some special thing from a world that isn't theirs, if they do not come from a world with magic or, say, someone doesn't come from a world that has guns, learning how to use that thing will become that much harder and take that much longer. I want the game to remain flexible, but not insult the players who already have certain talents.
Also, characters can't learn specific versions of magic without the permission of the mod or the player it comes from if it's an OC-style magic (say Blythe's.) Characters can't randomly access the magic of Lina's world, or randomly access the magic from Blythe's world. Different magics, different settings, etc.
The CU magic centered around this specific realm focuses on the presence of Lucifer and Metatron, and to use it is to draw bits of power from them. - This is tentative, as I have to finish wording this, but it's going to be in the wiki. <3