In
Nemesis
Asimov had "placed considerably more emotion than was customary," by which he meant, I suspect, that the action of the novel was driven more by character than by the logic of the ideas. Pitt is motivated by his concept of a better human society, but the others are influenced by love, ambition, uneasiness, or, most of all, by obsession. Marlene, for instance, has an intense desire, against all reason, to visit
Erythro. Later that is explained as the shaping of her desire by the prokaryote mind. Her mother is driven by science but influenced by ambition, by her love and later dislike for Crile, and by her love for Marlene. Siever Genaro, the head of the project on Erythro and perhaps Asimov's representative in the novel, is the only one who doesn't fear Marlene's gift for deciphering people's secrets from their body language; he is rational except in his love for Insignia. Crile is moved to insist on a place on
Superluminal
and then to insist on certain procedures in their search by his obsession about the daughter he hasn't seen since she was ten months old, and by his memory of his sister's untimely death as well as her resemblance to Marlene. And so on.