I have mentioned in many different posts that I am lucky enough to be surrounded with a wide variety of friends who cover the full range of any number of spectra. A part of why I appreciate this is of course because I have many people with whom I can consult, share time, learn from, and teach. However, as a writer there is an added perk: Having a lot of friends is like owning a personal grab-bag of characters who can be thrown into any story at a moment's notice.
There's a story I am working on right now about an atheist - let's call him Frank - who comes face-to-face with an angel. Now, I have friends who are atheists and friends who are very confrontational, but are any of them a real good fit for Frank in this story? Not even close. At this point, I start picking through the different qualities and characteristics of all the people I know or have met, and start scavenging the pieces I need. Like a scrap man in a junkyard, I grab this and that, pulling off little parts and fixtures that I know would fit perfectly into my vision of Frank and leaving the rest out. I know a stubborn insurance agent who can bench press 280. Let's take the stubbornness and leave the shredded physique behind. The atheism I can grab from a writer friend of mine, but leave behind the sense of humor.
In this case of our friend Frank, I also need to consider what qualities would make Frank interesting. I know plenty of people who would deny a truth staring them in the face - is that what I want in my story? Or do I want a story where Frank sees something he can neither believe nor deny, then chooses to change his mind? Depending on how I want that story to go determines what other parts I grab from the bag. I might want to pick the temperament of one friend who would just as soon punch a statue in the face for looking at him wrong to provide active conflict. Maybe my Buddhist friend would be a good example for a more peaceful resistance. Whichever route I choose, I make sure to bring out the qualities that would create the ideal amount of conflict and tension before rising to the conclusion.
Now, the fun part of making characters this way is that if/when your friends read the story, they might recognize or identify with little pieces here and there, and say, "You know, this Frank guy kinda seems like Ramon in a certain way." If they say that, and you did borrow qualities from Ramon, then it's a sign that you did a fine job translating the person's particular trait to the page.
Of course, you have every right to create your own characters from the whole cloth of your mind, and that's fine. Just remember that you have a whole Rogue's Gallery of character traits to tap into already, and nothing's wrong with a little scavenging now and then.