MacHugh appears briefly in the Aeolus episode. His biggest moment is re-enacting a speech by John F. Taylor on the revival of the Irish tongue. Later, Stephen tells him "Parable of the Plums," which he very much enjoys.
In his discourse with Stephen, we see that MacHugh is actually something of an intellectual and one of the first men that Stephen openly respects. The two of them are able to banter back and forth in highly erudite language that goes over the head of other people present (like Myles Crawford). Beyond this, we don't get too much of a sense for MacHugh. Like Stephen, he is taken with historical antecedents for the contemporary Irish condition. He compares them to the Greeks and then to the Jews. But MacHugh is not an artist. He is an intellectual and while he enjoys discussing such ideas, it is clear that he does not struggle with them to the degree that Stephen does.