During the episode where Marvin the Martian is introduced, the other kids make a point of avoiding him because he's "weird"; this has the unsurprising effect of making him even more shy and lonely. Taz, the Cloud Cuckoo Lander up to this point, finally catches on to what the other kids are doing, then goes over to Marvin and says, "Taz be Marvin's friend." Even more heartwarming when you remember that Taz was the only one who accepted him from the start.
The episode "Cock A Doodle Do It" has Foghorn Leghorn's only appearance in the show. Here he is depicted as a self conscious, low self esteemed rooster kid, as Tweety helps him finally break out of his shell to stand up to the other Jerkass roosters.