@s4pn4ps1ut Hi ♡, I do have some ideas for them(sorry if they not nice♡)it's only what I can think of at the moment.
For Maya x reader: maybe the reader can be Travis's sibling and they are a doctor(ortho or neuro)in Grey's Sloan and has bumped in Maya and crew quite a few times but doesn't get along at first but gradually both realize the feelings for one another (kind of a slow burn romance)
For Andy x reader: the reader is a firefighter at 19 but is a lieutenant like Jack and maybe either Ripley or maya's Sibling, the reader is in love with Andy but hides it well so Andy doesn't notice but the only one who knows about the reader's feelings is Dean because he is their person, an injury on call cause Andy to realize her feelings but is scared to lose another important person so she doesn't admit out loud.
For carina x reader: the reader can be Andy's sibling and meets carina the same time as Maya and falls for her ,but also realizes Maya likes carina as well so she tries to pretend she doesn't like carina and acts cold around her,but carina knows that the reader is hiding something so she intends to find out and bond with the reader ultimately falling in love with her and admiring the selfless sacrifice the reader was going to do for Maya and carina.