In "Dialogue on Immortality and Personal Identity", which character's position on personal identity and immortality most closely resembled Descartes' view?

Descartes is similar more or less to Gretchen, not just because Gretchen took a liking to philosophy, but because Gretchen wondered if there was life after death and she was more or less on the no side.

However Sam tried to convince her throughout the story and that is what Descartes did. He tried to get to know if this was true through the means of phsicology.

Explanation: Gretchen Weirob was a philosophy teacher and Sam Miller is her friend. Gretchen decided to spend her last days debating on whether life after death is possible and on personal identity.

Descartes considered the body and the soul to be ontologically separate but interacting entities, each with its own particular attributes. He then sought to specify both their mode and site of interaction; the latter he deduced to be the pineal gland. The pineal was to become, in the words of Geoffrey Jefferson, “the nodal point of Cartesian dualism.”

Descartes succeeded in eliminating the soul’s general physiological role altogether and in circumscribing its cognitive role to the human species. Descartes’s writings about death show that his concept of the soul clearly implied both mind and the immaterial principle of immortality. It had to mean both things, for no one had ever conceived of survival after death without a mind to verify the fact of continued existence, to enjoy its pleasures, and to suffer its pains.

We now know that immediately below the pineal gland there lies the mesencephalic tegmentum (the uppermost part of the brain stem), which is crucial to generating alertness (the capacity for consciousness), without which, of course, there can be no volition, cognition, or reason.