First off, Super Faith seems to be winning the poll so it may be the first story I will be working on during the summer.

Anyways, I thought of the brother's sins

These are all the Eeveelution Sins
Jolteon- Envy
Vaporeon- Greed
Flareon- Wrath
Umbreon: Sloth
Espeon: No sin (loyal)
Leafeon: Gluttony
Glaceon: Lust
Sylveon: Pride

So the brothers Sins:
Mario-
Flareon- Wrath (easily tempered)
Vaporeon- Greed (coins) *could have been both of their sins though*
Glaceon: Lust (I don't think Mario ever evolved into a Glaceon yet though but this is the sin for Glaceon. And do I have to explain this one?)

Luigi-
Jolteon- Envy (Jealous of Mario's popularity)
Leafeon: Gluttony (could be more of Mario's sin but whatever. Luigi could be the same way)
Umbreon: Sloth (laziness, dream team)

So I didn't even mean that to happen but it did and it fits.