I think my favorite dynamic that I created in the core five (pittlings + Samira (idk is she considered a pittling?)) knowing each other's crushes in the workplace and constantly teasing them about it. (my ships btw!!)
Trinity is the most brutal to Dennis about his crushes regarding the two married attendings who make the poor boy go red in the face every time they look at him. She'll just constantly make obscene gestures and noises whenever they're around Whitaker.
Samira likes to nudge into Victoria to get her to knock into Mckay so much that Mckay thinks Samira is a tripping hazard and just likes to maneuver Victoria out of the way whenever the R3 comes around (unintentionally making it 100x worse for Javadi)
As payback for Trinity bullying all of them all the time, they like to very loudly talk about Garcia to her when the surgeon is very nearby causing her to always turn her head and see the R1 with a bright red face as she tries to yell at her friends without making anything too obvious. ("Wow Trinity! you are so right Garcia's nails do look amazing today!!!" "And weren't you just saying how pretty her hair was!!! I totally agree!!!" "I will kill all of you right now if you don't shut up")
Dennis and Victoria like to magically disappear when they're with Mel and Langdon appears. The only time this really backfires is when Langdon rounds a corner with her and see the pair standing right there like a couple of deer the road.
One of the more subtle ones was whenever anyone ran into Dr. Walsh they'd always ask her if she had seen Samira because "don't you two hangout a lot? oh... maybe I'm misremembering..." or just talk about Samira in her general vicinity so whenever Walsh comes into a trauma room with Mohan, there's always something to talk about. ("Your friends told me... etc., etc.,"