Dorothea's two suitors are the Reverend Edward Casaubon and then later, Will Ladislaw. These two men could hardly be more different. Casaubon is considerably older than Dorothea and extremely studious. He spends his days indoors reading books and suffers from weak eyesight as a result. His general health also appears to suffer and although he and Dorothea get married he dies not too long after. Dorothea is initially attracted to him because of his great intellect but she does not find marriage to him fulfilling.
Ladislaw is Casaubon's second cousin and a younger and much brighter, outgoing type. He works as a journalist and is interested in politics and law; therefore his sphere of work is quite different from Casaubon's. Casaubon recognizes him as a rival for Dorothea's affections and is jealous of him. Sure enough, Dorothea does end up marrying him after Casaubon dies.