Mercenaries would be a feature that allows players to sign up as a hireling for a time block. Below are some basic ideas.
A mercenary puts themselves ‘for hire’ (30 minutes at a time) and must accept any hire for a minimum of 15 minutes. The longer the mercenary allows to be hired, the greater the rate, money percentages, and bonuses to rolls (see below). Employment time starts when the patron and mercenary are physically near each other. Mercenaries are paid a flat rate (increments of 15 minutes) plus an extra percentage (20%) of money gained. Additionally, they gain +15 to any rolls.
The patron is responsible for any item repairs during this time block. During the time block, all items and money is kept aside in an escrow until the time block is completed. This is all managed by WoW and at contract end all money will be distributed and all items will be rolled on. If a patron cannot pay mercenary repair bill then patron items gained are forfeit to mercenary.
This system will allow for groups and even solo players to fill a roster for a difficult quest, or more likely, a dungeon or raid. Both patrons and mercenaries sign up using a ‘dungeon finder’-like system.
Even a rogue can hire themselves out to open lock boxes, etc.
A simple 0 to 4 star based rating system can be used for both patrons and mercenaries alike. Number of stars coupled with number of hires would affect percentages and rates, for both patrons (are charged more / less) and mercenaries (able to charge more / less).
Finally, mercenary player guilds can be created who are allowed to set their own numbers for percentages, rolls, etc. Perhaps even in-game perks can be awarded to such guilds for patron ratings and numbers of mercenary jobs.
This would help solve the issue of needing assistance, any provide a nice role playing element as well.