According to City and Guild, a Companion merchant could easily have sufficient income to completely support a small covenant out of his "pocket money" (the amount of money he gets to spend frivolously after all expenses, including living expenses, have been paid). In terms of Hooks, a covenant with such a generous Companion PC should be treated as having the Poverty Hook (after all, its "non PC" income is ZERO, and should he die or change his mind...) or should it be treated as having an income source comparable to the amount of money the PC provides yearly?
Could go both ways. Is he a loyal little doormat? Or does he expect spells, Items, maybe a longevity potion?
Quite, he might have some sort of long term special reason or just have an obsession for something, like books(and magi tend to get better libraries than most so one might consider it worth the money and maybe setting a condition about aquiring at least X new books per year or something) or magic(and knowing he cant handle it himself)... etc etc...
Yes.
Income source type "Charity" covers exactly this thing.
Or type "Wizardry" if the money is in return for magical services of some kind.
If the merchant is sponsoring the covenant for a special reason it might be proper to call it the "Dedicated covenant" Boon.
Hooks like "Beholden" and "Favors" are also possible.
And of course, "Contested Resource" and "Dwindling Resource" could be used to mark that the merchant will get cranky if not getting something in return or might be reducing sponsorship to the covenant, because of dissatisfaction or perhaps due to setbacks in his own income.
If the merchant is the person actually "running" the covenant, it instead becomes "Trade" as then its an integrated part of the covenant.
Also, don't forget that a Hook is a source of stories. If you have the Poverty Hook, even if you manage to make up the difference through another's money, then stories will result from the covenant's situation.
If you don't want stories about being strapped for cash and relying on another's generosity, then don't take the Hook. That doesn't mean that the situation is any different (the PC still pays for everything, and you have Charity as an Income Source).
Mark