This is sort of a thing I've already noticed happening, and I feel would be easily added by individual GMs, but something cool for them to add to their rosters could be "Guild Friends or Honorary Members". Basically a list of characters who are friendly/allied with a guild, but not actually in it for various reasons IC or OOC. GMs could allow them to participate in guild events, freely enter the guildhall, etc.
I know stuff like this is already a thing (though it's not officially listed anywhere). For instance, Decayuss is an ally to Sabertooth, and I know of someone who is going to be make a guildless mage who is an ally to SM, but not join it for IC reasons. Allies wouldn't really have anything particularly special, no access to guild spells, pets, or guild bonus when doing jobs with members of their ally guild. This honestly wouldn't even have to be an actual official mechanic of the site. I just noticed how some people allied themselves with certain guilds without joining and thought it would be cool for those guilds/GMs to recognize them somewhere by slapping it onto the guild info or into another section of the guild roster for an extra bit of flavor.
I know stuff like this is already a thing (though it's not officially listed anywhere). For instance, Decayuss is an ally to Sabertooth, and I know of someone who is going to be make a guildless mage who is an ally to SM, but not join it for IC reasons. Allies wouldn't really have anything particularly special, no access to guild spells, pets, or guild bonus when doing jobs with members of their ally guild. This honestly wouldn't even have to be an actual official mechanic of the site. I just noticed how some people allied themselves with certain guilds without joining and thought it would be cool for those guilds/GMs to recognize them somewhere by slapping it onto the guild info or into another section of the guild roster for an extra bit of flavor.