The Lord sends Isaiah with his son (Shear-jashub) to meet with king Ahaz. Isaiah is a resident of the southern kingdom, and therefore loyal to his king, Ahaz. Isaiah’s sons figure importantly in both this chapter and the next. It is certainly possible that they are his actual sons, but their presence is more important for their names than their persons.
In this case, Isaiah is accompanied by a son whose name means “a remnant shall return.” (Ludlow, p. 140.) At the beginning of this chapter, there is a foreshadowing in the name of the son which portents the coming events. Surely a remnant will return, but not until there is a destruction and a driving out that will require such a return. The name is therefore the important part here, and not the presence of the son himself. The son comes so that the name can be brought into the beginning of the prophecy as a powerful portent.