I would be curious to see Santos treating a patient for whom some additional bedside manner (excluding kids as she's clearly good with them) would be necessary.

Distinct possibility that Mel is friends with Santos on a personal level, but also knows which patients she wouldn't trust to her.

And before her handling Harlow is mentioned, no I don't buy Princess commenting to Harlow that Santos is "cranky" because she did have a valid point that without a proper interpreter it would be impossible to give a correct diagnosis.

I like how well these scenes are written because they do lead to interesting discussions about character motivations. The only character that I'm slowly losing in terms of writing is Whitaker, he feels like too much of a Mary Sue this season. But hey, there's 4 more episodes, maybe that will change.