And I don't mean visually, which I'm sure plenty of people have done essays on because they are all so SHAPED fr, but...
I mean writing-wise. Personalities.
Pavel and Paige are my favorite example, because they just play so well off each other. Pavel being, legitimately, a raging lunatic (I love him) bounces so well off Paige actually having a bit of a conscience and a tragic backstory that makes her more sympathetic. You really don't feel any sympathy for Pavel and you're always rooting for Paige against him which is just... really good writing, man! You're led along that line of thinking far before Beck tries to change her mind and turn her to good. (Which honestly makes him failing to do so even more devastating, so again, good writing...)
But Pavel isn't played off as stupid or completely incompetent, and he nearly succeeds (does succeed? mans was playing 4D chess) in the date night episode. He's right about certain things (such as Tesler being generally incompetent - I mean he is, really, as scary as he can be at times) and a real threat. Which also makes Paige's blind loyalty to Tesler even more tragic! which again - good writing! :D
The dysfunctional dynamic between the three of them that still feels like family at times ('Never underestimate our dear Paige!') is just really well done!
Tron and Beck are fairly obvious, the classic jaded and grumpy mentor and eager young student, see also: Batman: Beyond. 8) But also, I love how this changes over time - they go from legitimately bickering and disagreeing (See 'The Renegade') to Tron cracking jokes and gently teasing him about his crush on Paige in Rendezvous. Tron starts to loosen up, give him more ground, and legitimately let him make his own choices and mistakes (Iike a good dad, sniff).
And in the end we find out Tron trusts him deeply, after it's established the guy has serious trust issues (See 'Identity') because in 'Terminal' Tron trusts Beck with his life, literally. Trusts Beck to save him before he can be repurposed. Before Beck suggested that plan, he was content to die rather than become Clu's slave (see Scars Pt.2 where he sasses Dyson about that).
I just have a lot of feelings about them ok!! Everyone is so three dimensional! Even Zed, who starts out as a really stereotypical character grows a bit by the end. I love everyone in this bar T_T