You should say:

　　Who he/she is

　　what he/she did

　　When you first knew him or her

　　and why you are interested in him/her

　　参考范文：关于司马光的个人迷恋(词汇极度个性化且丰富)

　　I have a sort of crush on Sima Guang, a prime minister from the Song dynasty,about 1000 years ago, and I find this crush rather queer, hard to explain, as he was a diehard conservative, while I embrace libertarian ideas. On most issues, I agree more with his political opponent Wang Anshi.

　　Sima Guang was held as a model Confucian politician and scholar by his contemporaries and later generations for his honesty, self discipline and sense of morality. He was strict with others and stricter with himself, too tough to be charismatic. In politics, he was irrationally uncompromising, which to a certain extent damaged the prospects of the nation and his own career. Su Shi, one of his proteges, irritated at his obstinacy, nicknamed him ‘Sima Bull’.

　　I’m sure he isn’t the social, easy-going type, definitely unromantic. We wouldn’t get along well even if we met. But ever since the first time i heard of him in a primary history class, about a story that him cleverly saved a play pal from drowning in a water tank when he was just a little boy,I do find him cute in many aspects.

　　He was a faithful husband. Ancient China was a polygamous society. Men were allowed to marry a wife and take concubines. Although rigorous prerequisites were imposed, only men upholding high moral standards followed the laws to the word. And Sima Guang was one of the few. He refused to take a concubine even when his wife was found infertile and his conditions fulfilled the prerequisites. He got ruffled up whenever his wife pressed the issue.

　　It might sound a little hypocritical. Only those who know him truly are sure of his sincerity. In ancient China, people believed children (especially male ones) to be a testment of one’s integrity and God would punish those who commit moral or other despicable crimes with a childless curse. And a man has the obligation to continue his family line. Sima Guang must have been exceptionally courageous to face the possible moral pressure.

　　Sima Guang wasn’t a born saint. He used to hang out with courtesans and wrote some amorous poetry in his youth. On a few occasions, his opponents playfully confronted him with those poems. Imagine his embarrassment!

　　He was a neat freak. He was the editor-in-chief in compiling China’s first chronological history book, 'Comprehensive Mirror to Aid in Government' (资治通鉴), which covers the entire Chinese history from the Warring States period to the foundation of the Song dynasty. The project took 19 years, and the piles of drafts filled two rooms. People were awed by his team’s serious attitude when reading those drafts. Every page was neatly written, with only a minimum of corrections.

　　He was indifferent to wealth. When his wife died, he had to sell his only three acres of farmland to cover up the funeral cost.

　　Sometimes self-denying could be sexy.