  We propose a giant graviton expansion for Wilson line operator indices in
general representations. The inserted line operators are specified by power sum
symmetric polynomials $p_\lambda$ labeled by partitions $\lambda$. We interpret
the partitions as the structure of fundamental string worldsheets wrapping
around the temporal circle. The strings may or may not end on giant gravitons,
and by summing the contributions from all brane configurations consistent with
the specified partitions, we obtain the finite $N$ line operator index. The
proposed formula is consistent with known results and passes highly non-trivial
numerical tests.
