Thomasin is a definite foil to Eustacia, even in terms of coloring. Thomasin is associated with light, sunshine, and color while Eustacia is strongly tied to darkness, night, and the color black. Aside from their physical differences, the two have very different personalities. Thomasin is practical and is a self-professed country gal; Eustacia is romantic and dreamy and longs for the city. But both are women of very strong wills who make the best of bad situations. And both of them have a temper, though we definitely see Eustacia's more than Thomasin's. There's a sense, in the few interactions they have and in the way they speak of one another, that these two women could have become friendly if circumstances had permitted it.