Audrey's Come to Jesus talk with Nathan in "Spiral" (which I think was their first major fight). After she and Nathan find out that the cracks in Haven were caused by the Chief with the appearance of Nathan's biological father as a stressor, she gives him a stern What the Hell, Hero?? rundown of his relationship with his father ending with "I don't care what issues you two have, let's just find him." Which is ironically the point that Nathan started out from. She gets bonus points for bodily shoving Nathan into a seated position when he refuses to listen to her the first time. Which doubles as Fridge Brilliance when you realize that it probably shocked him into shutting up because unlike everything else he can actually feel her pushing him.
Vince Teague, when a muscular ex-con threatens his little brother in the first season finale.
Ex-Con: I see you again, I'll kill you.
Vince: Didn't work before.
Pretty much everything Dwight does and that includes the wendigo episode where he carried a hungry child wendigo to safety while his leg was caught in a bear trap. Did I mention that wendigo's were attracted to blood?
Audrey tricking the murderous pyrokinetic into blowing himself up in "The Hand You're Dealt".
"Over My Head": Duke absorbs Daphne's blood to gain his temporary Super Strength and saves her from her sinking car.
From the same episode, Tommy Bowen thoroughly owning the Teagues when they try to blackmail him. These two guys have spent pretty much the entire series being about as unhelpful as humanly possible, so it was satisfying to see someone finally get the better of them.
"Double Jeopardy": Duke luring Lady Justice out of hiding by confessing to the murder of Harry Nix.
"Real Estate": Nathan going Guns Akimbo against the haunted house to allow everyone to escape. Followed by Audrey blowing up the house while throwing Rolland Holloway's "This is all your fault." taunt back in his face.
"Magic Hour Part 2": The Bolt Gun Killer interrogates Vince and Dave, but even when he takes a sledgehammer to their legs, they don't scream, just grunt and swear they will kill him when they get out of this.
"Burned": They finally get an opportunity to milk some straight answers out of a suspect, and while Audrey nearly grabs the Idiot Ball and avoids it (she had a good reason, but still), Ginger steps up to make sure it happens. Shame Ginger lost her ability after that.
"Survivors": Lexie reassembling a gun in a few seconds and using it to scare off some thugs.