In the novel Five Little Pigs, Caleb Jonathan of the firm Jonathan & Jonathan was the family solicitor for Amyas and Caroline Crale. He hosted Poirot with great courtesy in his home in Essex when Poirot called on him for background information on the murder of Amyas Crale.
Jonathan correctly devined that what Poirot was really interested in were the characters of the people involved, to "get under the skin" of the criminal. As Jonathan's firm had served the Crale family for generations, he was able to give Poirot detailed background information about the various personalities.
Jonathan considered Amyas Crale to be an egoist, a trait which ran through his family. He got his artistic trend from his weakly mother, and his driving power and ruthless egoism from his father. The Crales "never by any chance saw any point of view but their own." Of Caroline, Jonathan told Poirot about the incident where she had thrown a paper-weight at Angela Warren, but he disagreed with the impression given during the trial that this showed Caroline was a woman of ungovernable temper. To him this was not true at all. Philip Blake was "always a nasty, money-grubbing little brute" while Meredith Blake was a "namby-pamby" always absorbed in his study of botany, butterflies and birds. Elsa Greer Jonathan likened to a crude form of Shakespeare's Juliet. She was a "spoiled child of fortune". She saw Amyas as her prize and went all out to get him. She was "A predatory Juliet. Young, ruthless, but horribly vulnerable!" She appeared to win but then Amyas died, and so she was left with nothing but hate for whoever killed him.
Despite the fact that Jonathan liked and admired Caroline, like many of the lawyers Poirot had interviewed, he did not doubt that she had killed Amyas.
To Poirot, Jonathan was quite "a character". "After the insipidity of young George Mayhew, Mr Jonathan was like a glass of his own vintage port."