As much room as you need. You are well in tune with what we have all accepted and have an understanding of how I interpret matters. I suggest you team up with Fixer, so you can have a solid authority to judge rules and hold me to it.
Okay, so I've got a few more questions/thoughts...
Is this really the case? I thought Sa Dragonera was completely uninhabited and basically uninhabitable. This could really change my thoughts on where I wanted to take things, since I was thinking a mystery/exploration adventure, which makes much less sense of Arnau lives there.
Marko, I had an idea I wanted to run past you. I'd like to make it such that the vis source has never actually been harvested or even found. My thought is that a magus of Barcelona was exploring on Sa Dragonera and detected a potential vis source on the island, somewhere below the surface (likely in a cave of some sort). He didn't have time to find it at the time, so left it for later. When the covenant went looking for it the next season, the vis source was gone, so they determined it must be one that is perishable (maybe a fruit that spoils or something), so the magi have to harvest it in a certain season (I'm thinking probably Spring).
Marko, did you have any thoughts on the amount of vis the vis source provides? I have an idea of what art I want it to be, unless you had something specific.