Just to quote from the lore blog Saint Arthur on generally how 'magic' manifests. 

[i]"It’s generally possible to gain some form of power or ability in Fallen London by messing around with weird things. Lilac’s got her irrigomancy from the Nadir, Presbyterians getting super-immortality from the Mountain of Light, Flukes and Mt Nomad get to yell Correspondence hard enough to explode stuff, Slivvy’s got weird urchin lightning stuff from Storm… that’s just a few things off the top of my head. I mean, I guess it depends on your definition of magic, but basically everyone and everything is involved some way with some weird stuff, and so that weirdness ends up rubbing off onto them. I don’t think anyone gets to summon skeletons or throw fireballs though."[/i]

So to put it in the simplest of terms, it falls under the sorta lovecraftian rules... magic tends to be less something you do and more something that happens to you. Some people more than others. (Magic has happened to all my characters in varying ways...but that'll become clear as things go.)

You might gain particular abilities as a result of it. You might become possessed by an ancient god and go on a murder rampage.

As far as I'm aware fro my talks with Echo, the RP does feature the wider lore of the universe, as brought up in some of the character backdrop, but is more about preserving the general feel of it than being exactly in line with the existing lore (which tbh even seasoned players often would not know a lot about...I certainly don't know the extent of it.). I'd advise to just go for it and I'm sure Echo (or I, if asked) would be happy to suggest a way to make what you're going for work if anything need a tweak. =)