My brother was the middle seat of a 3-3 configuration. The people in the window and aisle seats were fairly young men who knew each other.
They spent most of the trip talking loudly to each other right across my brother. Trying to be politically correct as best I can, these people were not Americans and were apparently fairly dirty and crude and my brother was actually afraid of contacting some sort of infection from what was passing right in front of his face.

He politely asked him if they would like to switch seats are they could be adjacent but they refused.

My passive brother did nothing but I'm wondering if the FA would've done something if he contacted her.