In episode 8, Freeman gives us this horrifying anecdote:
"This window kind of reminds me of when I came home from school and there was some dead guy stuck in the smashed window of my apartment. He'd been trying to break into the place, but instead gutted himself on the insulated glass. That was not fun trying to explain that to the police."
Not sure what's more disturbing: How gruesome that story is, or the fact that Freeman found it to be more irritating than anything else. Then again, you could get some Alternate Character Interpretation out of this: Maybe Freeman was once more normal and stable, but the psychological trauma of things like that happening turned him into a dysfunctional lunatic with next to zero empathy.
Alternatively, he was already so crazy that he didn't really care. Or, he's in denial about smashing a guy through his window in a fit of rage.
Also, even thought Freeman has violent thoughts it doesn't necessarily mean that he'll act on them. They're entirely in his head, and it's heavily implied that the viewer is seeing a part of Freeman that nobody else sees when talking to him. We're seeing inside the thoughts of a person, and that's much different than meeting them face to face.
That's not particularly relevant. Besides, there are points where he's definitely speaking out loud to other characters. A pertinent example is when he asks a scientist if he'd like to be his human shield.
There's also the fact that this has probably happened to people in real life. In fact, knowing Ross,* (the first Freeman anecdote in the show — the squirrel in the power lines — actually happened, just at a different school and to one of his professors) it might be based on something he heard in the news.
Gordon Freeman's basically a deranged, unstable madman, who can be victim of weird episodes where he loses control of himself. For example, the "Class is in session!!" or "No comment!!" parts in episode 9. Sure, they were cool and everything, but what if he had other episodes like those in the past? Or if he could have more in the future?
One Bullsquid gives Gordon some, and we get to hear about it:
Gordon: Yeah, that's right, moan! MOAN! That noise is exactly what I'll be thinking about when I try to go to sleep tonight! And I'll be dreaming about you sucking out my eyes with your tentacle face, while I'm nestled up against a stack of rotting corpses, then my intestines will burst with insects crawling out of them, then the screaming...
A lot of Gordon's inner monologues qualify, given his Cloud Cuckoolander mindset. Here are a few examples:
"Hey, that's a ladder! That means this is legit; this might actually go somewhere! I mean, it probably leads to a room filled with poison gas and a bunch of dead people that look just like me, but I don't know that, so there's room for hope, I guess."
When he does fall in, he panics when his Geiger counter starts going off and he sees a security guard. "RADIATION. DEAD BODIES."
"If any of these worms get in my hair, I swear to God I'm just gonna freak out. Yeah, worms get in my hair; the power fails and the lights go out; then some old guy with a raspy voice starts laughing and poking me with a stick. That would complete the experience."
"I was expecting to look down there and see this giant eyeball looking up at me, angry at me because I blew off its eyelashes or something, then the whole building starts shaking and I guess I'd just ball up and cry, because what do you do when something that big wants to kill you?"
His theory that the tentacle monster in the rocket test chamber is actually just the hair of a larger monster.
At one point he theorizes about killing a security guard and using his intestines as rope. He only decides against it because it would be too slippery.
His theory that the headcrab zombies are getting more intelligent, evidenced by two of them playing with corpses as if they're puppets, and another pushing over a computer server to trap him in a room. And he starts speculating that the zombies might eventually start dressing up as the soldiers.
"Captain Trigger Finger", considering the guy put a bullet in at least three unarmed scientists before Freeman got to Lambda, despite being meant to protect the scientists. And Gordon isn't wearing a helmet, so if the Captain snuck up on him...
Freeman: Some people thrive in chaos a little too much. Everyone else sees disaster, he sees a human shooting gallery... I bet if I wait a few hours and come back, he's going to be wearing a necklace made out of ears and painting pictures of demons or some crap on the walls with the scientists' blood.
Freeman's all-too-plausible theory that the "reactor" in Lambda Core is nuclear in nature, and that it's on the verge of a meltdown. A potential China syndrome is nothing to laugh about. Even Chernobyl never got that far.
Freeman's breakdown when he first gets to Xen. It's definitely funny, but also disturbing considering how genuinely afraid he is. Not to mention the fact that he starts contemplating suicide.
Gordon's reaction to the Nihilanth is the worst in this regard, as it's surprisingly dark for this series, not helped by being a Call-Back to his encounter with the Tentacle. There he remarked that he might have totally broken down had the Tentacle been an insignificant part of a larger, now angered creature that wants to kill him specifically. Now he's face to face with a giant Lovecraftian monster that's pissed off at him specifically and makes this abundantly clear when it psychically snarls his name at him. The Nihilanth is Gordon's greatest fear about the invasion realized and he stumbled into it completely by accident!
Gordon: (thinking the Nihilanth Portal is some sort of radio) Okay, let's try this centre orb here. Maybe it does something. Check-check, mic check, hel— (teleports) —lo? (notices the Nihilanth turning to look at him and starts breathing heavily as his heartbeat becomes audible)
In Episode 54, Freeman meets an Eli Vance-lookalike that tells him he knows "more than any one man should". Freeman brushes it off, but as he ventures through Xen he comes up with a surprisingly disturbing theory on how Black Mesa has been operating. Namely, they've been sending hundreds of migrant workers to Xen (pulled from the ranks of the security guards, explaining why there were ads all over the place in the earlier episodes) with no intention of recovering them. Some fell to their deaths, some exploded across space, and others were slaughtered (Freeman witnesses human flesh being hacked into pieces in episode 65).
Freeman, episode 67: There is a fucking Mengele on the other end of those teleporter controls, and he's not going to stop until he's teleported the entire world here, or else somebody kills him.
Freeman, episode 68: What was it that guy said to me? "I know more than any one man should"? He must've been dead serious when he said that.
And what happens if Freeman doesn't take the G-Man's offer? He gets teleported to a world of G-Men monsters with no ammunition.
Freeman's Mind 2
It's minor, but Gordon stating that the G-Man's breath "smells like paint" is a very creepy detail.
An In-Universe example for Gordon when he sees a Strider for the first time due to mistaking it for a Tripod.
At one point in episode 5, Freeman gets strangled by two barnacles at once, leading him to vomithis brains out, then state he's traumatized.
Freeman (still getting his breath): I have to kill it, kill it before it's too late, kill, keep killing.
Also from episode 5, Freeman's encounter with an attack helicopter is harrowing due to the fact that he's utterly powerless to destroy it. All he can do is scramble from one point of cover to another desperately looking for a way out while sounding like he's in the throes of a goddamn panic attack.
Freeman spends the majority of his time on the airboat avoiding attack helicopters throwing explosives and cops at him. When he's not driving through hell (or getting stuck making his own ramps) he's going through security checkpoints trying to survive hordes of soldiers trying to kill him. No wonder he has a panic attack at the end of Episode 13.
Ravenholm. Just... Ravenholm. It was terrifying in the real Half-Life game and even Gordon's entertaining remarks and the lack of creepy music don't tone it down much. Between the hanging dismembered corpses, the crazy ramblings from an initially unseen Father Grigori, the headcrabs both normal and poison jumping from the rafters, and the electrocuted body stuck to the fence, it's easily the spookiest place Gordon's seen yet. Even he gets badly skeeved out when he sets fire to three zombies, who scream in agony.
Gordon: ...this isn't why I got into physics. This is the difference between "theory" and "practice", right here. I don't want this shit.
