If you're looking for a pacifist parsons, don't call up Parson Trulliber. He immediately forces Parson Adams to go look at his hogs for sale, and then he flies into a fury when Adams isn't interested. Oh, you want to borrow money from this guy? Forget it. Of course, when his wife sees him "clench his fist," she intervenes (2.14.4), but you'd better believe he won't hesitate to defend his farm and his hogs if he has the chance.
The peddler's an example of a guy who doesn't seem important until the very end of the novel. If you haven't read to the end, a major spoiler is coming your way: the peddler reveals Joseph's true parentage. Why does he do it? Well, his old mistress revealed the secret on her deathbed. But he's also "inquisitive from the time he had first heard that the great house in this parish belonged to Lady Booby […] and that Sir Thomas had bought Fanny […]" (4.12.1). In other words, this dude's something of a detective.
Let's be honest: it takes a bit of gumption to figure out the significance of Joseph's strawberry-shaped birthmark. It also demonstrates empathy, since this peddler's basically trying to solve a mystery that involves a bunch of strangers. We already know that the peddler helped out Adams when he was in a bind, so we can guess that this guy's pretty much invested in helping out anyone who needs it.
Once upon a time, Mr. Wilson got up to some serious mischief. Parson Adams is completely scandalized by Mr. Wilson's history, even though Mr. Wilson turns out to be a decent guy: upon hearing about all of Wilson's youthful affairs, for example, Adams wonders "what wicked times these are?" (3.3.8).
Okay, it's also not like Wilson made one mistake right out of the gate and instantly repented. Nope, our gentlemanly friend keeps up his rakish lifestyle for at least a few years.
Getting thrown in jail seems like it was the best thing that happened to Mr. Wilson. After all, it allows him to clean himself up a bit and meet his future wife, Joseph's real mother. But Mr. Wilson seems to feel that his sinful life led directly to the greatest tragedy of all: losing Joseph when he was just a wee babe. Thinking through that logic, maybe recovering his eldest son is a sign that he's finally made up for his crimes.