fèn covers the 'share / portion / lot' senses — what is allotted to someone. It shows up as a bound noun in compounds:
身份 (identity, one's social part),
缘分 (fated bond),
本分 (one's proper role),
安分 (content with one's place),
过分 (beyond one's share — excessive),
部分 (a portion). It rarely stands alone.