Silver Spoon seems like a spoiled little rich filly, but in reality she's not. It's mostly an act so as to be friends with who she thinks to be popular; in this case Diamond Tiara. She's a follower and will do what Diamond does when the two of them are together. When away from Diamond, Silver Spoon is tolerable, almost friendly toward her classmates, even "blank flanks," so long as they don't become overly annoying.
Silver Spoon lives with her mother and father and is the only child of those partners. Her household can be considered Upper Middle Class and she will be want for nothing; hence the source of her cutie mark. She has parents who genuinely care about her, teaching her good manners, concerned with her progress in school, and her choice of friends. As such they are not very fond of their daughters affinity with "that Tiara filly." Her mother would much prefer Silver to befriend Rarity's younger sibling Sweetie Belle.
That said, Silver Spoon and Diamond Tiara have been long time friends as the two families are practically neighbors. Silver cares very much for Diamond and is concerned for her friend's well being at home. (There is an assumption that Diamond Tiara's father takes heavily to the salt when he's home and can be abusive.) Due to their long friendship together and lack of siblings of her own, Silver Spoon considers Diamond Tiara like a sister. (It is unclear whether Diamond shares this sentiment.)
Silver Spoon is a complex character. Silver knows what she's doing to the CMC is wrong, but it's fun to tease them and she can't abandon Diamond. Caught between doing the right thing and sticking with Diamond Tiara, she is loyal to a fault. She goes on with the belief that one day Diamond will realize what she's doing is wrong and will stop being so mean and stuck up. She also believes that Diamond needs to know she has a friend in Silver Spoon and wants to be there for her friend should something bad happen to her at home.
She had a little crush on Tornado Bolt and wanted in the worst way to bring him into Diamond Tiara and her little clique. When she saw that wasn't going to be possible she let him go. Initially she just couldn't bring herself to be mean to him. However, recently Tornado Bolt has really become insufferably timid which annoys her.
She struggles with Math, and Social Studies & History bore her. She's good at Grammar, Reading & Spelling though. She's more athletic than Diamond Tiara, but will likely hold back or play dirty so as not to make Diamond feel or appear inept.
Silver is good friends with the Barista at Ponyville's Bistro & Cafe and enjoys a tall, double shot, dark chocolate in 1% milk, steamed to 95 F. or dark chocolate milk shakes. She's a developing chocoholic.