Steve is at first a careless, rich and spoiled teenager – or so it seems. Beneath the posturing he struggles with the knowledge that he was adopted, his strained relationship with his critical father, Rush, and a lack of substantial relationships with his mother and friends. Once Steve meets Brandon, like Kelly, he quickly takes to the stable Walsh family and his friendship with Brandon provides him with a stability he had hitherto not known.
Brandon stands by Steve through his crises and, at times, immature schemes that sometimes involve illegal activities. Steve also develops a close bond over time with his ex-girlfriend, Kelly, and the two become almost like each other's familiy. After college Steve grows into a more responsible person, an accomplished adult, while still maintaining his zaniness and enthusiasm. He also starts a family and marries Janet Sosna.
Steve starts attending high school in 1989 and pretty immediately starts a relationship with Kelly Taylor. They enjoy being together, care for one another and start sleeping together, which is Steve's first time. They are together for a year and somewhere midway through their relationship, Kelly's best friend, Tiffany, starts making a move on Steve, who rejects her. Kelly is hurt and ends their friendship, but Steve and Kelly stay together. Kelly breaks up with Steve at the end of their freshmen year, which leaves him heartbroken, although he would never admit that to her.
Devastated at their break-up, Steve alternates between being mean to Kelly and talking dung about her, and trying to get her back. He meets Brandon at a party at Marianne Moore's house and they begin a friendship.
Steve starts college eager to join the fraternity his father was in, Kappa Epsilon Gamma house, both because it's what his father expects, but also because he feels it's the only way to truly feel like he is a part of the school. While Steve is worried that Brandon has no interest in the frat, he does get accepted and starts living in the house of constant partying. This takes a toll on his relationship with Celeste, who feels like Steve has lost interest in her, which is further compounded by his flirtatious nature.
Adapting to the bro-douchey KEG behaviour, Steve cheats on Celeste and sleeps with a girl, who turns out to be unstable and falsely accuses him of date-rape after he breaks things off with her. This is a horrible ordeal for Steve, who knows that their sex was consensual, but he eventually receives support from Kelly who clears his name by telling the story of how Steve saved her from sexual assault in high school. Steve is relieved that the truth comes out, but concerned that he hurt Laura's feelings and talks to her, apologising for his behaviour. He comes clean to a heartbroken Celeste, who leaves him for good.
At Christmas his junior year of high school, Steve sets out to find his birth parents, only to discover that his biological mother had passed away years before.
When looking for Karen, Steve tracks her down to Al's diner only for him to divulge that Karen has passed away. Shortly Al reveals that he is her father, and for the first time ever, Steve meets his grandparent. Together, Steve and Al visit Karen's grave and Steve asks to keep in touch with his newfound grandfather.
A former star of a hit family series, Samantha is very much at the center of attention at the Sanders Mansion, where she lives with her son. She is a single mother, as Rush is rarely around until Steve is an adult and although she's mostly focused on image and her life of glamour, she later proves to Steve that she loves him and has his best interest at heart.
It was revealed years after Steve searched for Karen that Steve's adoption was true of only one parent, as Rush is indeed his biological father. With this information in the open, Steve and Rush finally began settling their differences for good. Rush would later help Steve start up a publication with Brandon.
Steve expressed interest in many women throughout the course of the series, much like his friend Brandon, but would end up having serious relationships with a select few. These bonds would help to develop his character with regard to consequence, monogamy, and responsibility.
- Main article: Steve and Kelly
Steve and Kelly dated for about a year their freshman year of high school, but Steve bragged about sleeping with Kelly, which caused her to break up with him. It is also implied that Steve's generally conceited, careless attitude at the time was what led Kelly to leave him. After an acrimonious split, the two spend a lot of time together due to their respective friendships with the Walsh twins, and eventually their meanness toward one another fades into friendly bickering. This is also a result of Kelly apologising to Steve for not being a better friend to him, when he realised he was adopted, as Kelly was the only person he told. Eventually, they grow closer and become great friends, to the point where Steve wants to start something up, but the timing is off as Kelly at this point is with Brandon. Despite this, the two would remain close friends well into their adult lives.
Steve won the affections of Celeste Lundy while competing on a dating game show, and began seeing her soon afterward. Though he cherished the relationship, Steve lost Celeste following an irresponsible moment in which he became unfaithful. However, the two regained a portion of their friendship while spending time together at a carnival.
- Main article: Clare and Steve
Steve would later begin a long-term involvement with the semi-snobbish Clare Arnold. While largely playful at first, both would gradually reveal more mature and sensitive sides through their dedication and love for one another. In contrast to his high school relationship with Kelly, Steve displayed more restraint during arguments with Clare; he was generally less cocky and more interested in compromise. This would often help to reinforce the genuine affection that existed between the two. At the end of their relationship, Clare reluctantly left Steve and Beverly Hills to spend time with her distraught father.
Steve finally met 'the one' in Janet Sosna, an emotionally guarded woman who worked on the Beverly Beat publication and initially wanted a merely sexual relationship with him. In time, however, the pair would come to realize and acknowledge their true feelings, and developed a deeper bond that resulted in marriage and the birth of their daughter, Madeline. Thus, Steve concluded the series as a loving husband and father.
- Steve also made brief guest appearances in early episodes of Melrose Place, the franchise's second series, accompanying his friend Kelly Taylor to Los Angeles (while joined by Donna Martin and David Silver).
- Steve's parents divorced when he was 5.