My dad has bumped somebody off their FC upgrade.

He was flying back from HKG, and they EUA'd him on the EWR-IAH leg perhaps 3 days prior. [That was a few years ago, now we all know how rare a EWR-IAH EUA will clear early.] CO98 was a little late coming back from HKG and CO assumed he'd miss the connection and give away his FC seat. However, my dad has no checked luggage and made it to the original flight in time, boarded and they had to move the other guy, who was apparently battlefielded, to the back.