These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternate Character Interpretation: Lots of the "good" characters have this. Jessica Pearson showed no remorse over some rather nasty pranks she played when she was younger and occasionally mistreats Louis. Harvey is very smug and possibly a hypocrite about Mike's pot use. Still, they're unquestionably the heroes of the program. Louis, an initially villainous character, has shown a more human and sympathetic side.
Dry Docked Ship: Donna/Harvey. Possibly. No longer up in the air as of 3x06.
Foe Yay: Harvey and Travis Tanner, especially in the boxing ring.
Growing the Beard: While season one established itself as another quirky show about a genius fake lawyer learning on the fly, season two introduced a well-woven and tightly-written story arc, that focused on internal dynamics of the firm, Xanatos Gambits and a Magnificent BastardBig Bad who could go neck-to-neck with Jessica.
Harsher in Hindsight: In the beginning of Inside Track, Harvey tells Mike to cancel on visiting his grandmother (see below quote). After Asterisk and High Noon, it's a lot less funny and more heartbreaking.
Harvey: Is she dying?
Harvey: Then cancel on her.
Hilarious in Hindsight: While Louis may proclaim to be a Lannister, he probably wasn't quite expecting to have to face up against the hatchet man of Lord Varys.
Ho Yay: Mike and Harvey, mainly. Part of the reason it developed a devoted cult following online. Now has its own page here.
Jerkass Woobie: Louis is shown to have a severe inferiority complex that causes him to constantly try to prove how competent he is and that he is a better lawyer than Harvey. When he screws up a case it is heartbreaking to see him admit this to Harvey and when Harvey treats him as an equal he temporarily loses all his Jerkass aspects. The worst part of all this is that Louis, when on his game, is genuinely a good lawyer. This is taken Up to Eleven in Season 2, where it seems like the universe seems to have developed a great dislike of him despite the fact that he's trying to come out of his shell, gets even worse after the incident with Daniel Hardman, and worse than that in Season 3 when he genuinely tried to befriend Mike and work with him after Harvey refused to forgive him, only for Mike to go back to Harvey at the first opportunity. He's slowly becoming less of a Jerkass and more of a Woobie the more the show goes on.
Lawful Evil: Louis. It's pointed out that he may be a douchebag but he lives and breathes the firm and would never betray it.
Harvey's secretary Donna can manipulate seasoned lawyers like Harvey and Louis without much effort and does it with style.
Harvey believes that the only way to make senior partner at the firm is to be one. He dislikes Louis because he is merely a Manipulative Bastard and lacks the 'magnificent' part.
Jessica, Harvey's boss, has outwitted and outplayed Harvey on several occasions. Such as in episode three during the McKernan Motors situation, using both Harvey and Louis to further the firm's ends.
Jessica's former former partner Daniel Hardman is most certainly one as well. To put it in simple terms, in his first appearance,Harvey threatens to reveal Hardman's shady past to his daughter if he comes back...and Hardman proceeds to come clean. He then spends the entire season getting back in the firm's good graces and even resolves Tanner's lawsuit against the firm, after which he gets the firm to vote him as the main managing partner. To top it all off, turns out he forged the incriminating memo that caused Tanner's lawsuit in the first place.
Moral Event Horizon: Hardman definitely has crossed this when we discover that he forged the incriminating memo that caused Tanner's lawsuit against the firm, showing that he cared more about looking better than Jessica and Harvey than about the firm he supposedly was trying to save.
Selfish Good: Harvey. Most of his Pet the Dog moments are really just new ways to show off or stroke his ego, though he does have the occasional genuine pang of conscience.
Louis, again, with the arrival of female Harvard Law School rep Sheila Sazs. Harold describes her as a "Female Louis" and wonders if the world would be destroyed if they touched. An aghast Mike doesn't want to think about them touching.