Here's an non-comprehensive list of everything M.A.G.I.C went through in their internship year aka the first 3 seasons of grey's anatomy. the first 61 episodes. I'm not sure how to break this down so I think I'll go character wise, and mostly in order of most to least believable. I'm not including their patients, time spent studying, actual working hours, stuff they do outside the main scope of the program (meredith spending time with her mother, george shooting a turkey with his family) etc. I'm also not commenting on the timeline of how everyone seems so close even though, again, this is supposed to one calendar year. this is just the stuff that happens to them on a personal basis.
(hilariously, richard webber is supposed to retire as early at the very first episode of the series and yet james pickens jr is one of two remaining main characters as late as season 22. (they haven't announce the cast of S23 yet, but i have to assume he's going to stay))
ALEX
he seems to have the most "normal" internship year. he falls for izzy, but they don't officially date. He does fail what seems to be the oral portion of the STEP 2 exam- but he retakes the test and passes. He sleeps with various women, most notably Nurse Olivia. This results in a syphilis outbreak at the hospital. He meets Ava- who is actually Rebecca. (as a patient) He has Addison Montgomery punishing him by putting him on a near permanent OB-GYN rotation, and he was kind of a typical asshole of the 2005 variety (forces himself onto Meredith at one point, bullies izzy, freezes in the elevator) but other than that, a believable internship year. he also is passively involved in the whole Denny Duquette thing, and he moves into the main house in S3. before that we don't know where he lives.
CRISTINA
Now it may seem weird to have her here, but she also has a relatively normal year. She falls in love with a guy, has a miscarriage, moves in with the guy, and gets left on the alter. it's pretty fast in terms of actual time (again, this happens in the span of one year) but not utterly impossible. of course, burke gets shot, and she bears the burden of studying and doing his surgeries but that also feels doable- if improbable- to me. she's supposed to be the gunner of her class, the best intern so it tracks that she can keep up with advanced procedures. we learn about her dead father, and we meet her mother. she's obviously involved in a lot of the meredith stuff, and she helps with the denny thing. she's also there for the bomb but burke sends her away so she's just in brain surgery with derek, and mostly it's her friend going through that.
GEORGE
i struggled between george and izzy because a LOT happens between them. George's marriage is written to be hasty though so he ultimately lands here.
is in love with meredith. moves in with her. sleeps with her. gets mad at her. makes up with her.
moves out of the main house and moves in with cristina and burke
is burke's "guy" and discovers burke's tremor.
gets syphilis from Alex. (via Nurse Olivia)
meets and dates callie.
bailey names her baby after him when he helps deliver the kid (not even getting into bailey having a baby even though she wasn't pregnant in the first season let alone naming him after an intern she's known for less than a year but whatever)
breaks up with callie. helps with the LVAD thing
dad in the hospital for cancer. dad dies.
marries callie in vegas.
sleeps with izzy. (falls in love with her?)
agrees to have a baby with callie
applies and gets accepted to mercy west as a transfer.
fails his intern exam and has to repeat his intern year
IZZY
also moves in with meredith
gets bullied by Alex for being "doctor model"
throws a party for her hockey boyfriend but they end up breaking up
dates alex for a bit but they break up when she sees him necking nurse olivia
struggles on her mom's birthday but eventually calls her.
makes thanksgiving dinner with burke?
has time to decorate the apartment for christmas.
meets a patient- denny duquette. - who gets rejected for a heart transplant and leaves the hospital.
starts sleeping with alex during the bomb in the patient episode.
denny comes back and gets fitted for an LVAD. izzy and denny spend a lot of time together
izzy breaks up with alex after he's an ass to denny.
denny is offered another heart but izzy learns he might not get it which causes her to cut his LVAD wire.
denny proposes and izzy accepts.
denny dies, and izzy quits being a surgeon.
she's gets an $8.7 million inheritance. (they have known each other like.... 6 weeks or something be so fucking serious)
izzy gets reinstated at the hospital despite being a millionaire, because all she wants to do is a "running whip stitch." she's not allowed to do surgery though, and has a bunch of hoops that legal and hr make her jump through
izzy decides to spend her inheritance building a free clinic for Seattle Grace. This happens in 8 days. (stfu fr)
alex tries to kiss her but she's not ready.
izzy is not happy about george's marriage. they fight about it.
sleeps with george. is convinced she's in love with him.
is fully allowed to perform surgeries again just because the chief said she could. (no HR or legal oversight?)
and finally, our plot armor queen. a lot of this is derek related but it just gives me such whiplash just watching it, i can't even begin to imagine what she's feeling. also the context of this being one calendar year is very important to me. (also v ridiculous, i love this show)
MEREDITH
sleeps with a guy who turns out to be her attending
is late to her first day of work.
mom has Alzheimer's but that's a big secret because mom's a super famous surgeon (didnt know famous surgeons were a thing)
gets roommates she wasn't sure she wanted. they're all up in her space and stuff. she ultimately appreciates it but cmon.
is sexually harassed by alex
bailey learns she's sleeping with an attending and gives her crap. (izzy and george are also awful about it but i'm counting this as one thing)
tells derek about her mom and he gets her mom into a clinical trial.
her boyfriend's wife shows up at the hospital
she breaks up with derek even though he continues to pursue her. derek tells her he's getting a divorce. he does not do that. (pick me choose me love me famously happens here)
mom shows up to the hospital and everyone learns her secret in a super public way.
sleeps with a bunch of guys. one of them shows up to the hospital with priapism.
sleeps with george. they have a falling out.
puts her hand in a body cavity that has a bomb in it. Bomb squad guy explodes into pink dust in front of her.
meets her half sister who is pregnant and her dead beat dad's other family. susan is nice.
gets a dog. gives the dog to derek. is friends with derek till he calls her a whore. the friends breakup
helps with the cutting of the LVAD wire. learns her mom and her chief of surgery were having an affair. is friends with george again.
dog dies.
starts dating the vet. sleeps with derek at prom. decides to date them both. (don't ask about they prom, yes it's a real thing)
panties on the bulletin board
meets one of derek's bitchy sisters
half sister gives birth and has to deal with her dad, new niece at the hospital.
mark shows up and flirts with her. derek punches him.
has appendicitis. breaks up with vet. derek is being weird towards her. they get back together.
mother is lucid and says some pretty nasty things to her. (a regular tuesday night for some of us tbh).
she tries to drown herself in the bathtub. actually drowns. dies. meets a bunch of dead patients and dead dog. is revived.
mom dies.
deadbeat dad's wife makes and effort with her and is actually a good fake mom to her. bonds with her dad a little bit.
fake mom gets the hiccups and also dies. dad is drunk and straight up slaps her in front of everybody... (the slap is never brought up again)
doesn't write anything on her intern test.
her cheif of surgery acts like a fake dad to her and makes it so that she can retake the test later in the day.
she passes the test. (when the fuckkkkk did they study???)
breaks up with derek.