When developing the conclusion of a personal narrative, the writer should O explain the lesson learned from the experience.
describe the setting and introduce the characters.
O use details that build up to the climax.
o determine the format to be used.

Explain the lesson the writer learnt as your conclusion. Though if it meant to be an informative narrative, don't add any new information since it is not a story. Sum up what you have, say what you learnt from it.

taking into account that a theme is the central topic a text treats and can be developed through a story, play, poem etc. the following are themes that can be further developed:  

my best friend jeffrey has many unusual interests. (the story could be about each of the unususal interests)

once a man gives his soul over to evil, he can never go back. (this could be a saying or a proverb)

the three sheepdogs lay around the yard all day. (it could be developed detailing how each of these sheepdogs lay around)

a priest's collar has an unusual effect upon people. (it could be developed detailing the different effect upon people)

innocence is a powerful force in a world full of corruption. (it could be developed detailing how is a world full of corruption)

king lear is a play shakespeare wrote later. (it is just a sentence and doesnt give any idea or topic to be discussed in details.

evil often wears the disguise of innocence. (this could be a saying or a proverb)