Life leading up to The Sims 2
Alexander first appears in The Sims 2, where he lives in Pleasantview with his father and older sister. He has pale skin and glasses. He seems to share his father's intelligence, despite his young age, and he is enrolled in private school. This could be the reason most players give him the Knowledge aspiration when he grows up. Due to the apparent age gap between him and his parents, it is believed that he was born just before Mortimer had aged to an elder, resulting in a large age difference between he and his sister, Cassandra Goth. However, there is a picture in the family album of Alexander being held as a baby by Cassandra when she was a teenager, and Mortimer is shown as an adult, so it's likely he was born a day or two before Mortimer aged.
He has a memory of being taught how to talk by Bella (however, Mortimer has memories of teaching him all three of his toddler skills), so she was probably abducted shortly before he became achild. He likes to play with toys, play chess, and occasionally play piano. When the family is first played, he is four days away from becoming a teenager.
If Mortimer is already dead by the time Alexander goes to college, his mother will be the parent who drops him off at his dormitory, even though she's supposed to be missing. This could hint that she is, in fact, alive somewhere, but it may just be the game mechanics.[1]
Through SimPE, it is possible to see that he has a hidden Fortune aspiration token, hinting at the aspiration EA wanted for him, though the player can choose any aspiration they wish when he becomes a teenager.
Life leading up to The Sims 3 (Nintendo DS)
Alexander re-appears in The Sims 3 for Nintendo DS, this time with a very different appearance and personality. He lives in the town of Beacon Bay, and is married to Cecilia Goth. His family bio states that he and his wife have lived in the town since the beginning, and that their gloominess is a result of having a father named Mortimer, and it can be assumed that his father is already dead in the game. He wears a top hat and suit, looking very much like his grandfather in The Sims 3. Strangely, his hair is orange, meaning that he may have dyed it. He is an acquaintance of Holly Alto, and his traits are Neurotic, Brave, Outgoing, and Ambitious. Unlike his father, and like his grandfather, he chose to work in the Business career instead of Science, and is a CEO at the start of the game. (In The Sims 2, his bio and skills give the idea that he is destined to be a scientist like his father.) He and Cecilia start off in the game with §50,000.