i think one of the most interesting things about the end of season one is the insight we get into John's friends and hunting community. in 1.20, we meet daniel elkins, in 1.21, we meet caleb and pastor jim (who we heard of in 1.10 & 1.18), and in 1.22, we meet bobby!
after they meet ellen and jo in 2.02, sam says
You ever notice Dad had a falling out with just about everybody?
but that's actually not quite true. it's true john had a falling out with ellen, bobby, daniel elkins, and tara* (9.16). but he doesn't seem to have had similar fallings out with and jefferson (mentioned in 1.10), pastor jim, caleb, gordon (2.03, 2.11, 3.07), deacon (2.19), travis (4.04), martin (5.11, 8.09), or fred jones (8.08).
and i think there's actually a lot revealed about his character and the character of his friends based on who he fell out with or not. sure there's some folks we don't have enough information to speculate about (caleb, jefferson, daniel, tara to some extent) but there's a lot to think about given the little information we have about the others.
for starters, we have bobby who clearly pushed back against john not treating dean (and sam) as kids (7.10). we don't know if that was a contributing factor to their falling out but it is the only evidence of tension in their relationship we see. we have ellen, who has strong feelings that her daughter shouldn't be hunting. so we have to conclude that she would at least have had some judgements about how john was raising his kids. even if their ultimate falling out was more to do with bill's death, it's hard to imagine them not being in tension about kids hunting.
and then we have the folks john didn't fall out with. pastor jim, who was at least okay being the back up call for kids left alone for days. there is obviously a high chance that he had his objections to this but that he thought he could at least do some good staying in their lives. but all we can do is speculate.
but there's something distressing about each of the others on the list. gordon seems to have shared a lot of john's black and white thinking about the world. and we have this:
SAM: I - I thought you said he was a good hunter.
ELLEN: Yeah, and Hannibal Lecter's a good psychiatrist. Look, he is dangerous to everyone and everything around him. If he's working on a job you boys just let him handle it and you move on.
it's not really clear what she meant but gordon does intentionally endanger sam to try and prove all vampires are evil.
travis, very similarly, thinks of monstrosity as an inherent way of being and not a choice. so much so that he all but forces the situation to play out in the most murderous way possible. martin also seems to share this mindset. and when dean defends benny's character, martin says
MARTIN: Glad your dad wasn't around to hear that. He'd have a mind to take you both out the woodshed and show you what's what. Half inclined to do it myself.
that's a heck of a series of folks who have a really similar mindset about hunting and monsters.
then we have deacon is physically violent to the incarcerated people in his control. and fred jones who
DEAN: Yeah, that guy gave me my first beer. I don't even think I was double digits.
SAM: Right, yeah. Me, too.
and, well, that just sucks.
it's just really interesting which hunters john kept around him. both 2.03 and 12.06 make very clear that john was extremely cautious about taking his kids to hunter gatherings of any kind:
GORDON: Word travels fast. You know how hunters talk.
DEAN: No, we don't, actually.
SAM: Yeah, no, Jody. We… we know you’ll be fine, but… you know, we never go to hunter gatherings, outside of bars. Dad always said they were trouble, so…
and some of that was about his general paranoia and fears about sam etc. but it also reminds me of what dean says to lee, krissy's dad in 7.11:
DEAN: Don't thank us. Quit. Your daughter's 14 years old. She's already a hunter with a-a kill under her belt. I'm not trying to be a dick, but what do you think that does to her life span? She could still be a regular kid.
john seems to have been, at least to some extent, avoiding exposing himself and his kids to a wider community of hunters some of whom might have said something similar to the above.
*she's upset he never called her but it doesn't seem like they had a real falling out.