I wonder how often a FO drops a trip and another picks it up only to have that Captain look on the schedule and say hell no I ain't flying with that guy and trade the trip. The only Captain willing to fly with said FO is one that even that FO can't stand so he drops the trip and Sailor Jerry gets the trip.

See the trouble two people can make? . The reality is Captains should be able to put FOs on no fly lists til the only people that can be paired with pilots on either lists are people already on the lists.