oncoming_storms 71.4: Who or what do you think has the most influence over how you portray your character?
Ask me this question for almost any other character I play, and you may get a different, more interesting answer. However, I think that in all cases the canon should be one of if not the most influential power over a character's portrayal. I think this is perhaps doubly important for a minor character like John.
But when I say 'canon,' I don't mean just the facts about him. If I were going off just facts, I'd never have the confidence to portray John. Even including speech patterns, he is an interesting character, yes, but almost a flat one. It's easy to abuse his problems and make him a full-blown villain. What makes John a real, true, breathing character for me, what made me want to take him on, what intimidates and worries me the most about playing him, is his body language. For me, this is the most important part of John's canon.
I hold John's body language as a stronger indicator of his personality and life than his own words or anything Jack says about him. Why? Because they are Time Agents, and Time Agents lie. This does not change when they 'leave,' otherwise John wouldn't count Jack as still being one of them. There's something about it that they can't leave behind, and both characters have more physical tells than anything else, in my opinion. So that, naturally, becomes the greatest canonical influence on my portrayal of him.
Other than that, I currently have a lot of free rein to do what I want with him. Lack of canon both hinders and helps, and a large influence on how I play out his family, at least, lies in some of Jack's discarded fanon. Back before Jack's parents were identified, there was the rather fun concept of him having three parents, somewhat spun from his pregnancy comment. I loved that idea. I thought it was great. I was disappointed a little when he turned out to be from a 2.5-children-and-white-picket-fence-named-Anakin type family (yes, the fence was named Anakin. For serious). John gave me the opportunity to take that same idea and use it. My current version of John's family includes two fathers and a mother whose biological role was basically wet-nurse. I have more detail set down in my head, but won't bore you with it.
The rest of my influence for John, who I don't read a lot of fanfic for, comes from other roleplayers. Jack-players especially, or anyone with ideas to do with the Time Agency, helps flesh him out more in my mind. I love playing with the different versions of John's past (so does he, boy needs to pick one), and the freedom of ideas that sort of flow around me via the roleplayers I stalk sort of associate with is really awesome.
He's not the easiest person to play off other characters, because he's so trigger-happy and unpredictable. Spill ketchup on his coat and you're probably dead, but spill ketchup on yourself and you may be dead too; on the other hand, he could just laugh at either situation. So maybe a tiny bit of influence comes from watching A&E's crime shows about murders and serial killers too much. I just hesitate to add that because it's so easy to see John as a serial killer or bad, and he's not. He's just... differently moraled.
By which I mean he has no morals at all.