I want to write a cool joining thread, but I was wondering if i could write other sub-characters besides Jaden just for Joining? Wolves he could just tear into on his way to souls, or do I have to get someone to write them with me (They are unimportant and it might be a pain because they are just being killed...)?
You can use NPCs (non player characters) like that (non-permanent, temporary) pretty much with no restrictions. Just out of curiosity, though, what were you planning? :3
It wouldn't be realistic for a whole pack of these NPC wolves to be killed off within 'Souls; such a thing would be noticed. If Jaden were to run into one or two wolves on the way to his chosen pack's borders that he dispatched, that would be alright and you would be permitted to play them in your posts as Jaden.
Keep in mind, though, if your character shows up dripping blood and clutching heads he just lobbed off, some of the packs might find that a bit distasteful. ;3