After Sandra turns against her friends, Crystal becomes very depressed, and is on the verge of bursting into tears. Just when she is about to cry, Sam, who has been a captive of Sandra until he managed to escape and whom she didn't know if he was still alive or not, appears. Cue one hell of a hug and happy reunion.
Mabel stopping Sandra from helping Lord Incubus, braving the demon's threats, discarding the possible help from said demon, and thus saving someone who was initially quite mean to her, all the while delivering a very nice Rousing Speech full of metaphors.
Sandra and Sam's reunion. Sandra was fully expecting him to hate her, and Sam went to see her ready to fight if necessary. When they do meet, they stare at each other before simply hugging. That very sweet moment was followed with them having a normal conversation, like old friends who didn't meet in a while.
Bloo to Crystal, also a Tear Jerker. Upon seeing just how full of love Crystal is, Bloo can't bring herself to condemn Crystal to life as a vampire and instead drops her in mid-air as, in her own words, "an act of love"