Mr Gardiner is Mrs. Bennets brother. Mrs. Gardiner is his wife
Mr. Edward Gardiner is the brother of Mrs.Bennet. He is a London businessman.
Both of them begin to play an important role from Ch.24 onwards when they arrive at Longbourn as usual to spend Christmas. Mrs.Gardiner and Elizabeth are particularly close to one another and often have important discussions regarding the central theme of the novel-the institution of marriage:"Pray, my dear aunt, what is difference in matrimonial affairs, between the mercenary and the prudent motive? Where does discretion end and avarice begin?"
In Ch.43 Elizabeth alongwith Mr.and Mrs.Gardiner visit Darcy's estate Pemberley. Darcy is no longer the proud man that he once was. He is very polite and courteous to all of them, and Mr and Mrs Gardiner testify that he is a fine person.
Mr.Gardiner plays an active role after Lydia's elopement is announced in Ch.46. It is he who follows Lydia and Wickham to London and with Darcy's help persuades Wickham to marry Lydia and thus help to prevent the Bennet family from being disgraced.
In Ch.52 Elizabeth receives a very important letter from Mrs.Gardiner in which Mrs.Gardiner reveals the generous role played by Darcy in compelling Wickham to marry Lydia. Mrs.Gardiner conveys to Elizabeth that Darcy did this only because he loves Elizabeth and that it is only a question of time before he proposes to her again. This letter is important because it confirms to Elizabeth that Darcy certainly loves her and she prepares herself to accept his second proposal.