"Stranded" provides the most wrenching demonstrations, up to that point, of Barbie and Ken still harboring feelings of love and regret after their breakup.
"Tutti and Todd" has a flashback of Barbie inviting the titular twins to come live in her dreamhouse, and promising to let them ditch the "special hats" for hats that don't obscure their faces. If only George and Margaret didn't send Tutti and Todd away...
In "Back to the Future", the first version of the future Barbie encounters is one in which Krissy had died, having microwaved herself as a baby. For a show that thrives on Hilariously Abusive Childhood, it's played rather tragically. Stacy takes her death the hardest considering she's usually the one who babysat her. Fortunately, Barbie prevents this future from happening by getting Krissy out of the microwave when she comes back to the present.
"60" has a Yet Another Christmas Carol-esque plot where the ghosts of Mattel past, present and future (Chelsea, Stacie and Skipper, respectively) show Barbie the alternate reality if she never signed her lucrative contract with Mattel. There, she is not only living in a lower class home and cut off financially by her parents for marrying Ken, but he's a jerk to her, he eventually leaves her for Yasmin (who is now the more successful of the two franchises and who is also nasty to her) and it's implied that the girls hate her as well. Furthermore, she's a lot less confident and happy in this timeline and whenever she tries to stand up for herself, she's immediately dismissed.
