OK. I'll do my best. I may mix stuff up with last series, lol, soz if so.
Maggie and Amelia moved in with Meredith. Her kids conveniently vanish when required. Bailey was made Chief because Hunt didnt want it anymore (because that happens) Meredith is what Bailey was.
Webber married Katherine but she's never in it.
Arizona and Webber spend a lot of time together at trivia nights - her pulling women him for the trivia.
Maggie slept with Delucca but she got too serious for him
Callie turned up for dinner at Merediths with Penny, and Meredith braved it out before having a meltdown and telling everyone Penny killed Derek. Bailey revealed she'd JUST given Penny a job. Penny then had an extremely hostile work environment yet somehow stayed.
There was also a storyline were Jo accused Steph of lying to get extra surgeries - she wasnt it was uncomfortable and weird.
Riggs turned up as an ex army guy apparently hated by Hunt and you know just gets a job there right away. No-one knows what the animosity is. It turns out he was married to Hunt's sister and Hunt blames him for her death in a helicopter crash.
Alex and Jo had some will they won't they engagement drama and Jo carried on struggling with Meredith in general.
Ben kept doing rash stuff at work until he got suspended for killing a pregnant woman.
April signed divorce papers knowing she was pregnant and Katherine planned to take her baby based on "fraud" so she issued a restraining order but then they sorted shit out.
I think that's it. God it's been a really "nothing" series this year.