I find that the hardest part of making friends isn't the walking up and saying hi, nor the getting to know each other well enough to exchange emails and know each others' names, but to move past the acquaintances stage and get someone to actually notice you and decide that you're worth spending time with. I think the quick-deep-bonds form when you get past that stage within the first few interactions. This is because you have a certain amount of social currency with strangers. Taking up someone's time costs social currency. If you eat through all your social currency without getting them interested enough in you to give you more, then you start coming off as creepy (see creepiness.txt).