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Molly Weasley is the quintessential mother figure, which means that she's the perfect representative of a mom. But she's not some sort of Leave it to Beaver variety of mom. She's probably closer to the moms on shows like Modern Family or The Middle. Molly is very funny, but she's also very real in a lot of ways – she isn't a perfect mom. Molly is alternately loving and strict. She'll hug her kids one minute and snap at them the next. And she has to be pretty tough since she has a very unruly brood to corral.
Then she opened her enormous handbag and said "I've made you all sandwiches [...] Here you are, Ron [...] no, they're not corned beef [...] Fred? Where's Fred? Here you are, dear [...]" (5.25)
Molly is pretty much the mom we would want to have, and she's definitely a mother figure to Harry. In a way, we can see what a good mother Lily must have been, and would have been, through Molly. Seeing Molly interact with her family, we know that she'd lay down her life for them in a heartbeat, just as Lily did for her son. So it's not surprising that one of the major character traits of Molly is her protectiveness. She's always looking out for her kids and she'll even fight with her husband about it, if she thinks that the peace of mind of one of her kids (including Harry) is at stake (4.3.26). Overall, Molly is characterized by her role as a mom, but her position as Arthur's wife is worth noting too – these two have a very solid marriage and function as partners. Even when they disagree, they act as a team.