The growing deployment of high-voltage direct current (HVDC) systems requires addressing the complexities of multi-vendor integration. This paper explores the evolving role of the HVDC integrator, which brings together components and systems from various vendors, ensuring compatibility and system performance. The paper reviews and compares existing literature on potential models for HVDC integration, particularly contrasting transmission system operator-led versus consortium-led approaches. Using input from different industry stakeholders, the paper further investigates different implementation models, ranging from joint ventures to publicly and privately owned competence centers. The discussion also covers the critical role of information sharing, software openness, and intellectual property protection in facilitating multi-vendor interoperability. In conclusion, while current business and regulatory frameworks present challenges, the paper envisions a long-term goal of a certifier integrator model, which could streamline the integration process as HVDC systems mature and become more standardized.