Mrs. Weasley isn't just a mother; she's the mother in the Harry Potter series. Her life seems to revolve around mothering her seven children – plus Harry – whenever she gets the chance. When Mrs. Weasley reads the Daily Prophet article accusing Hermione of toying with Harry's feelings, Mrs. Weasley starts treating her very coldly. Later, when Harry is recovering from his horrible experiences of the third Triwizard Tournament task, Mrs. Weasley stays by him to try and comfort him. Mrs. Weasley is the only maternal figure in Harry's life – certainly, Petunia Dursley doesn't fit the bill – and he's extremely attached to her as a result.
Mrs. Weasley's motherliness also makes her incredibly fussy. She starts a kind of mini-war with Fred and George over their Wizard Wheezes because she wants them to choose a more serious career. Even Bill Weasley, her eldest son, comes in for delicate hints such as, "your hair's getting silly, dear, [...] I wish you'd let me give it a trim..." (5.93).
Even if she fusses a great deal in daily life, Molly Weasley is still immensely attached to each of her children. When Arthur, Bill, Charlie, Percy, Fred, George, Ron, Ginny, Harry, and Hermione come back from the Quidditch World Cup disaster, the first thing she does is throw her arms around Fred and George and weep, "What if You-Know-Who had got you, and the last thing I ever said to you was that you didn't get enough O.W.L.s?" (10.11). She has a fierce temper, but Mrs. Weasley is loving through and through.
Her children repay Mrs. Weasley's huge loyalty in kind. When Draco Malfoy waves an article about Arthur Weasley in Ron's face, he shouts, "A picture of your parents outside their house – if you can call it a house! Your mother could do with losing a bit of weight, couldn't she?" (13.85). Harry, Ron, and Hermione obviously all bristle, because they love Mrs. Weasley and can't stand to hear a ferret like Draco Malfoy call her "porky" (13.88). Naturally, a fight ensues.