The character of Cole had a lot of potential on Supernatural: someone with a reason to hate Dean (who killed Cole's father.) Someone who hadn't drunk the hunter Kool-Aid. He could have provided an interesting critique of the Winchesters — but as of last night's episode, Cole is totally on the Sam-and-Dean fan bandwagon.
In "The Things They Carried," we're still dealing with the realization that there's apparently no cure for the Mark of Cain, and Dean is apparently doomed to go nuts the way Cain did. At which point, he will probably kill Sam. But Dean doesn't want to spend any more time trying to cure this, he just wants to spend whatever time he has left as a sane individual saving people from monsters. And the episode is supposedly an object lesson in how Sam has to realize that sometimes people (meaning Dean) cannot be saved. Because Sam is forced to kill a psycho dude that has been infected with a Khan worm that turns him nasty.
But the main juice of the episode comes from Cole — who, as he points out, nearly killed Dean out of a misunderstanding of this whole monster-hunting thing. Cole starts out the episode highly skeptical of Sam and Dean, and worried that they're going to kill his old buddy Kit (who they do in fact kill.) But after Cole gets infected with the Khan worm too, Dean goes to insane lengths to save him — thus proving, not just that Sam and Dean are heroes, but also that they have a huge double standard.
Seriously: Guy they've never met? Let's pop him. Guy they've hung out with? We are never going to give up on you! Cole never points out the obvious, which is that Dean was a demon when Cole went after him the first time, and even though Cole doesn't know how Dean got "cured," it's obvious Sam didn't just pop him. And Cole doesn't even know about all the times a Winchester was possessed by Satan, turned into a vampire, a soulless killer, or any one of a number of other things.
It's sort of heart-warming to see Cole come around to appreciating the sacrifice that Dean and Sam make, without ever getting any thanks other than really good hamburgers. But I'm a bit sad that the episode doesn't at least let Cole point out the obvious: sure, some people are genuinely beyond saving (and maybe this includes Dean this time, although probably not) — but the Winchesters try a hell of a lot harder when they know the person who's taken over by evil.
On the plus side, it was nice to see Dean and Cole applying logic to the problem of how to drive the Khan worm out of Cole's body. It was almost... scientific. And next week, there's a killer nun!