I was wondering about if one had only limited character currency what one should spend on, and I found allies quite interesting. How much can you tap from an ally? How much would an ally tolerate, and what kind of relationship is that if you tap an ally for a resource and how often does the character returns the favor.
This is one of those instances where players can act in a way that is unrealistic or socially in appropriate. One of my problem with this is that it sets a wrong impression and the danger of someone carrying that knowledge to the real world.
Having a friend in high places, has some very limited benefits - invitation to a great party or vacation you cannot normally afford (plus great company) but don't count on your friend doing anything that would making moochers out of his friends.
For starters, the GM should use allies as a source of plot and adventure hooks. These friends in high places will interact in a way where there is a limited amount of conflict of interest. He would help his friends with a lead, put in a good word, upper circles gossip and hearsay, provide insight about the higher ups of a institution (which speaks about the corporate culture - an organization becomes what it's leadership is like), etc...
As for the cavalry or being the big guns, financial backing, and some patronage power... That requires some detailing. characters is positions of power don't get there risking all that just for anything... His friends, the PCs, should consider how they might screw up the life of their powerful friend.
Definitely, when considering how much to spend on an ally (a peer vs a patron) consider how much of his own resources has the PC invested in himself. It kinda looks bad having invested more points in the ally than your self. The PC might become a retainer and not an ally.
Making your boss your ally - this is a conflict of interest. People who value their friends are in a better relationship if they don't trip over professionally their friends. Money between friends is complicated. Having experienced retrenching people and having been named in a labor complaint reinforces how this can be a really big problem.
Allies and contacts are complicated, the fast rule is use your empathy and your personal relationships as a guide. It's better to use them as adventure hooks, than for the players using them as resource you can just tap at any time.