So we have one major setting of Much Ado About Nothing: the home of the governor of Messina, Leonato, and the surrounding grounds. We do have a few scenes in the town (and on the streets) of Messina, but mostly we’re in the family home of Leonato.
And what of this family unit?
Leonato has an older brother, Antonio, and given some very small clues (his misunderstanding of the prince’s intention toward Hero [I.ii], the “waggling” of his head [II.i.109], and his relentless–to the point of comical–pursuit of the prince and Claudio [V.i]), we see him as a doddering old man. From this, we can either deduce that Governor is an elected position, or Antonio is so addled that he has either given up or had taken from him the reigns of power.
Leonato, of course, has the daughter Hero, his “only heir” (I.i.279). Was this ever his only child? Or is he like Capulet, for whom “earth hath swallowed all (his) hopes but she” (Romeo and Juliet, I.ii.14)? The opening stage direction of this play, in the Quarto edition at least, mentions a wife, Innogen; but she doesn’t speak in the scene, nor is she referenced again. There’s some critical opinion that this was a character that Shakespeare abandoned in later drafts of the play, meaning the Q stage direction is a remnant of an earlier draft. The stage production directed by Josie Rourke and starring David Tennant, and available on the Digital Theatre site, includes her for comic reactions in the first scene (when Leonato jokes that his wife told him Hero was his daughter), and then gives Antonio’s lines to her in later scenes (the Act One, Scene Two misunderstanding scene is excised from the play), and while it’s interesting, it certainly doesn’t change the nature of the play or its relationships at all.
Which leads us to and leaves us with… Beatrice.
She is a niece of Leonato (as mentioned both in stage directions, as well as in “cousin” references from Hero, and “niece” ones from Leonato). She is not Antonio’s daughter, however. Benedick makes no effort to get Antonio’s approval for marriage, as he does Leonato’s (V.iv, and possibly off-stage in III.ii). So who’s daughter is she? If she was the daughter of another brother, or even sister of Leonato, Benedick would, out of deference, approach the eldest brother, and that would be Antonio. If it was just a generic “cousin” reference from Hero, we might write it off as a close family friend, but Leonato’s “niece” references carry a weight.
She might be the daughter of a brother or a sister of Leonato’s wife Innogen. That would explain both the niece relationship and Benedick’s discussions with Leonato. But why is she living in this particular household?
A conjectured conclusion:
Beatrice has played in the household of Leonato an analogous role as the one I feel Katherine held in The Taming of the Shrew, a surrogate mother for Hero, put upon (almost to the point of exploitation). Beatrice here is not as obviously shrewish as Katherine, but there’s no mistaking the same kind of razor wit (as “she speaks poniards, and every word stabs” [II.i.234-5]). Unlike Bianca, however, Hero seems appreciative of Beatrice and what’s she’s done, as Hero would “do any modest office…to help (her) cousin to a good husband” (II.i.354-5), even though her wedding is not dependent upon the marriage of Beatrice.