Soo... Bajer learned the benefit of brain cells eh?

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The guilds consist of the following..
Artisans guild: though it exists, this is more a moderately wealthy guild of
nonmagical artisans(such as members of the expert class). Though they would be honored to have Vyncent around and would, quite honestly, be completely awed by the stuff he does, there probably isn't much that membership could provide.
fighter's guild: pretty much stands alone, attracts some non-fighter mercenary types..thinks of the companions as a rivaling business, nothing more, though they would probably like to have frank around more than they admit, bajer will probably provide too bad an image as anything but a mascot, certainly not a public figure otherwise

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mage's guild: again, more or less stand alone, they actually like the companions, as they aren't in the mercenary business, hire them sometimes, and ofcourse, there's vyncent. They will tolerate warlocks/sorcerers, but admission is more or less wizard/archivist only(Vyncent may still have a chance). Other guilds are somewhat jealous of their libraries, to which they reply that(usually to the fighter's guild) they will only allow the reading of their books for those that they can be sure will read the book over eating it. They aren't terribly familiar with or tolerant of psionics, but considering isobet's power, they probably will allow membership.
necromancer's guild: seperate from the mage's guild, and quite a rich establishment. These well-respected necromancers have researched a variant of the animate dead spell that allows the targets to retain their intelligence. Thus they are usually sought after for ressurections(or cheaper variants thereof), healing and (to some extent) servants. When a heavy debtor dies, his or her corpse may be sent to the guild to pay off the bulk of the debt, the corpse is then reanimated and sold as a servant, so zombie(usually skeletons, much cleaner) butlers and such are not an uncommon sight. The priests, as you might imagine, are midway between being disgusted by and jealous of the entire guild. They are well associated with the mage guild, though entirely seperate, and do not care much either way for the companions.
Assasin's guild: midway between secret and not, this is one of those that is well-known between the upper classes, but not often discussed. The members pride them selves on several things, including having received good education, behaving like most high society, and only killing for payment. They don't really like the companions at all, but will cope so long as they don't get in the way. Basically the entire companionship knows how to get here.((if you have read discworld books, this is pretty similar)) They may be interested in hiring frank, but it won't do their reputation much good.
nature/psionic/thief guilds and such: nonexistant, sorry.