To Elinor, the colonel is a faithful and helpful friend; to Mrs. Jennings, he is an eligible bachelor for whom she must find a wife; to Mrs. Dashwood, he is "a noble man" who would make an excellent husband for her daughter. To Marianne, he is elderly and unromantic.
The colonel's behavior is always honorable. He admirably fulfills his promise to his lost love, Eliza, and brings up her child. When the young Eliza is seduced by Willoughby, the colonel challenges Willoughby to a duel. He tells Elinor about it only because he wants to prevent Willoughby from harming Marianne.
During Marianne's illness, he remains devotedly in the background, helping whenever he can. He offers to fetch Mrs. Dashwood to Cleveland and on the journey back confesses his love for Marianne. "It came out quite unawares, quite undesignedly," Mrs. Dashwood tells Elinor. "I, you may well believe, could talk of nothing but my child; he could not conceal his distress."
Respecting Edward and wanting to help him, the colonel generously offers him the Delaford living, tactfully transmitting his offer through Elinor. His patience, tolerance, and kindness are finally rewarded when Marianne marries him, for "her regard and her society restored his mind to animation, and his spirits to cheerfulness."