A composition includes a fluoroelastomer, a crosslinking initiator, and a crosslinking agent. The crosslinking agent comprises a compound that comprises two or more structures represented by a formula (3), wherein R1, R2, and R3 are independently a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, or a substituted or unsubstituted aryl group, a plurality of R1 are identical to or different from each other, a plurality of R2 are identical to or different from each other, a plurality of R3 are identical to or different from each other, provided that at least one of R1, R2, and R3 is a hydrogen atom, and at least one of R1, R2, and R3 is a fluorine atom or a fluorine atom-containing group; n are independently an integer from 1 to 5; and each hydrogen on the benzene rings may be substituted.