William H. Macy (Magnolia) Magnolia

William H. Macy plays Quiz Kid Donnie Smith, a former child champion on What Do Kids Know? whose parents stole his winnings, leaving him broke and adrift in middle age. Anderson wrote the role to push Macy past his comfort zone -- into the kind of big, unguarded emotional performance Macy typically avoided.

Anderson believed Macy was scared of emotional parts

Anderson had worked with Macy in his earlier films and saw an actor who tended toward control and precision. He wrote Donnie Smith deliberately to force Macy into messiness.

Anderson wrote the role because he believed Macy was "scared of big, emotional parts" and wanted to challenge him. Macy's tearful breakdown scene -- Donnie weeping at a bar, confessing his loneliness to strangers -- was designed to push the actor past his comfort zone. (wikipedia)

Donnie's logic has collapsed but his need is real

Donnie is fired from Solomon Solomon's electronics store. He sits at a bar, drinking, watching a bartender named Brad who has braces. Donnie decides he needs braces too, believing they will make Brad notice him. The reasoning is deranged but heartbreaking: his parents stole his childhood winnings and his childhood, leaving him with no framework for understanding how love works.

When Donnie breaks into Solomon Solomon's store to steal money for braces, the theft is clumsy and sad. When he tries to return the money by climbing a utility pole to the store's roof, frogs knock him off. When Jim Kurring finds him injured on the ground, Donnie delivers the line that crystallizes his storyline.

"I really do have love to give. I just don't know where to put it." — Quiz Kid Donnie Smith (William H. Macy), Magnolia (1999)

Macy identified what connects all the characters

In a promotional interview, Macy described the common thread running through the ensemble.

"Julianne Moore and William H. Macy embrace the melodrama with finesse." — Elisa Guimaraes, Collider (2024)

Donnie is the film's most pathetic character in the original sense -- he provokes pathos. His storyline has the least dramatic weight in the ensemble (he never interacts with the dying fathers or their children), but his emotional directness gives the film its most unguarded moment. Anderson wrote the screenplay in Macy's Vermont cabin, surrounded by the actor's world while creating a character designed to break through his defenses. (wikipedia, screenrant)