Activities related to software requirements engineering and software architecture significantly contribute to the success of software development projects. In software engineering practice, requirements and architecture affect each other and should not be treated in isolation. However, from a research and conceptual perspective, the dependencies between requirements and architecture are usually investigated by focusing on either requirements engineering or software architecture. Therefore, the Fifth International Workshop on the Twin Peaks of Requirements and Architecture explored the relationship between requirements and software architecture in the broader context of software engineering in general. Based on the outcomes of previous editions of the workshop, this edition aimed at exploring the relationship between requirements and architecture in the context of agile software development. In general, the discussions at the workshop centered on proactive versus reactive software architecture engineering. We found that proactive architecture engineering provides benefits in certain contexts and domains. However, in order to succeed in competitive and fast-moving markets, reactive software architecture engineering may be more suitable, even though reactive architecture engineering could be difficult to in practice since it may require a different mindset from requirements engineers and architects.