Consider this example:
Ecce Marcus et Gaius. Hic canit, ille auscultat.
Here are Marcus and Gaius. The latter sings, the former listens.
When there are two or more things one could refer to, hic often means "the latter". The first of two can then be referred to with ille or is unless I am mistaken, but ille seems to be at least more common. I am not sure whether is is possible and when so, but I would like to figure that out.
Is there a difference between is and ille in references like this? That is, can I use is instead of ille here, or would it mean something else? In case of two (here Marcus and Gaius), would is refer to Marcus or Gaius, our would it not refer clearly to either one?
I think the usual latter/former pair is hic/ille, but I am unsure of the role of is. I am not sure it has any role like this at all.
This came up when I wrote an answer to a pronoun ambiguity question yesterday.