The use of science identity has been applied to a variety of investigations studying the inequity of many aspects of STEM education. This paper explores the possible limits and possibilities of expansion of science identity when the investigated subjects have different STEM subjects to develop identity in. Discussion about how figured worlds, Biglan's dimensions, and the ideal student concept could enrich the theoretical backdrop when seeking to understand how such identities are developed. Preliminary results from a longitudinal study, encompassing focus group sessions and classroom observations across the upper secondary school subjects Mathematics, Chemistry, Physics, and Technology are given. Preliminary data reveals students' distinct rankings and perceptions of each subject, reflecting variations in subject characteristics and expectations. The paper underscores the importance of recognizing diverse disciplinary identities to inform equitable STEM education strategies and calls for continued discussions and advancements in this realm.