They are like the rest of the Maiasaura. They are twins but it isn't known who is the firstborn, the middle and the lastborn. The males resemble Light, except for having blue-eyes, while the female is similar to their mother in appearance, although her eyes are more purplish.
They initially feared Heart when they meet, but were quick to warm up to him when their mother reassured them, the sister even offering a berry. Despite their bond the sister at least seemed wary of Heart if he was hungry and asked him if he would eat her, though he denies wanting to, he does warn her to be careful around the rest of his kind.