Rev reconciling with his brother Rip at the end of "Family Business".
Even prior to the reconciliation, it was clear that Rev was uncomfortable with his father's fawning and didn't enjoy how badly Rip got shoved aside; for all their differences, he adores his little brother.
Danger Duck feeling remorse for cheating the coin toss to see whether he or Pinkster would be adopted first in "In the Pinkster", as well as expressing hope that Pinkster can change for the better even when his old friend says to his face that he likes being bad. Considering what an egotisticaljerk he usually is, this says a lot about Danger Duck.
Lexi's smile at the boy playing the trumpet when he was unfrozen in the episode "The Hunter". At first she was startled by the loud noise so her smiling in appreciation of him being unfrozen was a small but nice part.