One of the two most interesting things about Mrs. Dashwood is that she has the same emotional romanticism as Marianne does. The two of them long and violently grieve the death of Mr. Dashwood.
[The] excess of [Marianne's] sensibility ... [was] by Mrs. Dashwood ... valued and cherished. They encouraged each other now in the violence of their affliction. The agony of grief which overpowered them at first, was voluntarily renewed, was sought for, was created again and again. They gave themselves up wholly to their sorrow, seeking increase of wretchedness in every reflection ...
The second interesting aspect is that Mrs. Dashwood does not support Elinor's sense in responding to emotional or practical situations. While she accepts Elinor's counsel on occasion, such as when choosing a new place to live, she accepts the counsel with if not negativity, remarks that show the difference in her own thinking from her daughter's.
But [Mrs. Dashwood] could hear of no situation that at once answered her notions of comfort and ease, and suited the prudence of her eldest daughter, whose steadier judgment rejected several houses as too large for their income, which her mother would have approved.
"And what," said Mrs. Dashwood, "is my dear prudent Elinor going to suggest? What formidable obstacle is she now to bring forward?"
Mrs. Dashwood adds a source of approval to Marianne's emotional propensities while adding an impediment to Elinor's steadfastness in sense. Elinor's character is presented as having exceptional personal strength in that she does not falter even in the face of her mother's criticisms.