In the game, Bella lives in Willow Creek in the Ophelia Villa with her husband, Mortimer, and their two children, Cassandra and Alexander. Bella is a young adult, 20 days away from becoming an adult. She has the Popularity - Party Animal aspiration. She works in the Secret Agent career as an Intelligence Researcher, and has two skill points each in Charisma, Fitness, and Programming. She is friends with her daughter and son, and sweethearts with Mortimer. She has no relationships outside of her household when first played.
Prior to the release of The Sims 4, Bella was referenced in many promotional material, starting with the first official trailer for the game.
Piano: In the Romantic and Classical menus (from Play Song...), there is a song named 'For Bella'. This could be any Bella, but as Bella Goth is probably the best known Bella in the whole of The Sims series, this is probably pointed towards her.
In the trailer, Bella is shown to have three traits, which are Romantic, Outgoing, and Active. She's also shown to have an aspiration of Friend to the World, and a Gregarious benefit. This version of her can be downloaded from the gallery, by SimGuruJill. The in-game version of her, however, has slightly different traits and aspiration: she is Good, Family-Oriented and Romantic, and has the Party Animal aspiration, but still has the Gregarious benefit.