Context: Pair programming (PP) is more relevant than ever. As modern systems grow in complexity, knowledge sharing and collaboration across teams have become essential. However, despite well-documented benefits of PP, its adoption remains inconsistent across software teams.

Objective: This study aims to understand the factors that facilitate or hinder team members' adoption as well as lasting engagement in PP.

Method: We have conducted an exploratory single-case study in a mature agile company in Norway. We collected data through two rounds of interviews with team members in different roles and performed a thematic analysis of the interviews.

Results: Our key finding is that multiple factors, related to the perceptions of how PP contributes to daily work, social dynamics and learning, efforts associated with engaging in PP sessions, company and team attitudes, resources, infrastructure, and task characteristics, affect PP engagement.

Conclusion: Long-term engagement in PP requires expected benefits with the practice being confirmed in firsthand experiences. Adapting the practice to each unique team, with insights drawn from collective learning, is also beneficial. Our findings will be beneficial for software practitioners seeking to make PP an integrated part of their team's workflow.