In the process of writing to two people I typed: "Are either of you free?" and was immediately called out by my grammar checker which suggested I should write: "Is either of you free?"
The second of these options feels intuitively wrong to me, as I am addressing two people so should be using the plural. However I feel this is tied up in the whole issue of whether a group should be referred to in the plural or singular sense, e.g.
Red Hot Chili Peppers is a band
Uses "is" to indicate that the band is a singular entity, whereas
Red Hot Chili Peppers are a band
Uses "are" to indicate that the band is made up of multiple people.
So, which is correct? "Is either of you free?" or "Are either of you free?"