I'm curious how I can increase relationship rank with an NPC without simply hacking the game. It's as simple as that really.

Is it only by performing very specific tasks, each already programmed in? Or are there general actions you can take with any NPC to become friends?

performing specific tasks they request.

OK - so if a character doesn't have a specific, scripted way to befriend them, then you must hack via console to improve status. Thanks.