Lovelace seems to me very real. We really beel the pressure of Lovelace's grasp on Clary's hands. We feel her trying to retract her hands.
Derision is perfect.
I put in the diagonals as this is a sort of poetry. What happens here is Richardson grants Lovelace depths because Richardson suddenly brings forward Lovelace's inward life in such a way as to grants him a moral conscience. The tone and sentence structures in this letter in which Lovelace responds directly to Clarissa in front of Belford gave a sense of a complicated real person who is not a lurid stereotype at all. Another may be that Richardson himself finds people to be less sincere or authentic and more amoral when they are imitating or modelling themselves on books. There is a certain irony here.