As she was growing up, Maggie was always overshadowed by Lisa in any form of academic award, as a result, Maggie felt an extremely strong resentment towards Lisa, and constantly fights her. She started to train her body and started to use Bart's skateboard. To separate herself from her, she changed her hairstyle and bleached it.
Maggie does care about her little brother, Eric, despite how much she teases him, and gets along well with Bart, who works at the local radio station, KBXL.
In Jake's Fan Comic Simpsons Generations, Maggie and Eric are both sent backwards in time when one of Professor Frink's machines breaks down, and has to cope living alongside her former self, and Lisa. Maggie contemplates just destroying Lisa, but doesn't.
When Bart, Lisa, Eric and Milhouse are captured at the museum by Sideshow Bob, Maggie comes to their aid and afterwards, Maggie wails on Lisa, but her baby self steps in to defend her older sister, Maggie, looking at Lisa, runs away remembering her own past, where she was once scared over a storm and Lisa comforted her. After that, Lisa and Maggie made amends.