I had a jerk call in for the first round trip of a four day trip because he didn't want to wake up. Then he took the trip back after I got back to FAT which took me out of contention for flying a four day trip on reserve, and I ended up with ready reserve for that day, plus a bunch of single leg trips that week causing me to get a hotel. I found out it was a guy in my upgrade class and told him what happened and he said, "seniority rules" There's a special place in Hell for these types off idiots.
I thought that if not rules-bound, then at least good etiquette says that if you bang out of a trip sick, and it gets reassigned and a reserve is called up to take it, then you don't (shouldn't) have the right to take it back, as you essentially forfeited it. If you want a make up trip, go find an open line and take it. Is that not the case?