Answer by taking a quote from the following article:

Alvin and the Chipmunks, originally David Seville and the Chipmunks or simply The Chipmunks, is an American animated music group created by Ross Bagdasarian Sr. for a novelty record in 1958. The group consists of three singing animated anthropomorphic chipmunks: Alvin, the mischievous troublemaker, who quickly became the star of the group; Simon, the tall, bespectacled intellectual; and Theodore, the chubby, impressionable one. The trio is managed by their human adoptive father, David (Dave) Seville. In reality, "David Seville" was Bagdasarian's stage name, and the Chipmunks themselves are named after the executives of their original record label.

In addition to having an IQ just north of Einstein, Simon possesses a dry sense of humor as well as keen wit. He is kind, gentle, logical, and at times poetic. He often takes charge when Alvin goes too far with his harebrained schemes. Although Simon tends to disagree with Alvin and even argue with him, he truly loves his brother and sticks by him despite everything. He wears glasses and blue attire, and has blue eyes. Simon plays the bass, bass clarinet, saxophone, bagpipes, tuba, and drums, among others. In vocal harmonies, he consistently sings the lower parts due to having a deeper voice than his brothers. He is shown playing the keyboard in the original open for the 1980s series. He was also shown playing guitar in a 1980s Hardee's commercial. Simon is often implied to have a crush on Jeanette, as she is like him in many details; wearing glasses and blue and purple attire and having a high IQ, possibly rivalling his own. However, he seems braver in standing up to siblings than her because Jeanette doesn't often stand up for herself when Brittany pushes her around, but like Simon to Alvin, Jeanette shares a sisterly bond with Brittany. In one animated episode, a chemistry experiment gone wrong resulted in Simon becoming a handsome, Casanova-like romancer. He called himself "Mr. Heartthrob" (an obvious parody of Mr. Hyde), and enchanted every girl he met before being returned to normal. Like his brothers, he was originally voiced by Ross Bagdasarian Sr. In the animated series and film, he was voiced by Ross Bagdasarian Jr. Matthew Gray Gubler voiced Simon in the live-action/animated film series.

did he have any struggles?
Although Simon tends to disagree with Alvin and even argue with him, he truly loves his brother and sticks by him despite everything.