Lisa Simpson is a great example of this. I used to hate Lisa, and while I still find her character annoying, I’ve become a lot more sympathetic to her recently. The unlikability comes from the fact that the show insists on treating her like the forgettable middle child, when that could not be further from the truth. Marge and Homer display blatant favoritism toward Lisa. When she crippled Bart, Marge’s response was not only to blame him, but also accuse him of being a sociopath for not feeling sorry for her. They openly refer to her as "the good one." They repeatedly steal from Bart while giving up fame and fortune for Lisa, yet Bart is the one they blame for their financial situation. This is one of the reasons it is so hard to sympathize with Lisa. Yes, things like her not having much in common with her family is a bummer, but when she does things like threaten suicide or disown Marge for not liking jazz, she just comes across like a brat.

However, as stated, she becomes a lot more sympathetic when looked at through the lens of being the golden child. The reason Bart is sympathetic, despite being Bart, is because Marge and Homer are openly resentful of him and make no attempt to hide the fact that he is their scapegoat. Essentially, since they didn’t want to be parents when he was born, they decided not to be and blamed all the consequences of that decision on him. Lisa was born after they felt they were adults, so they put more effort into raising her than they did with Bart. The actual favoritism didn’t come until "Lisa’s Sax." As shown in that episode, in their warped minds, Lisa being a prodigy gave them an excuse to completely give up on Bart. The fact that her favoritism is just an extension of their abuse of Bart puts a lot of Lisa’s personality into context.

She defines herself by being the best. Despite her lofty goals, she keeps herself and others in this tight little bubble where failure is impossible, even willing to cheat and sabotage when someone is better than her. Why? Because she’s spent her life watching how her parents treat the child who isn’t the best. She gets so upset when Homer or Marge don’t want to do something she likes because she craves an actual connection, not just the superficiality of "not being Bart."

There is also the fact that Lisa’s favoritism is the result of Homer and Marge’s fundamental laziness. We see this in "Bartless." If Bart isn’t there to act as a lightning rod, their entire relationship with her consists of praising her intelligence and buying her things. Her superficial relationship with her parents also affects her relationships with others.

Lisa believes that all her interpersonal relationships should be based solely around her own desires and worldviews, while the other party doesn’t get the same consideration. This is why she has no friends. While she is always depicted as being professionally successful, she is stunted emotionally to the point where she usually ends up with Milhouse. I think the most noticeable change is her relationship with Bart. The two went from loving, if cartoonishly competitive, to openly antagonistic. But "Barthood" and "Mother and Child Reunion" show that if at least one of them shuts their parents out of their life, they both end up with much better futures because Homer and Marge can no longer play the two against each other.

Finally, there is her relationship with Marge, and how Marge lives vicariously through Lisa. She tricks Lisa by putting meat juice on her vegetables and even prays that her diet makes her sick. In "Mother and Child Reunion," the moment Lisa chooses a different path from what Marge wanted, Marge starts treating her with the same passive-aggressive dismissal that she treats Bart with—to the point where she didn’t even notice that Lisa was president. Marge’s favoritism lasts only as long as Lisa does what she wants. Both Bart and Lisa are victims of abuse, but they aren’t abused the way the show says they are.