Possible to Use Different Neutral for Separate Runs of Same Circuit
While the neutral to the fan is on the same circuit as the other devices, the original drawing suggested that it is not in the same raceway or cable as the hot wires to the fan. This is not allowed under the code:


  NEC 300.3 (B) - All conductors of the same circuit ... shall be contained within the same raceway ... [or] cable ...


UPDATE: The revised drawing does indicate that the neutral wire is in the same cable as the hot wire(s). Consequently, the neutral is on the same circuit and in the same cable, as allowed under the code. While there are two hot wires, they are actually the same circuit and merely one hot, using two wires and switched separately for fan and light, a very common pattern.