This paper builds on two main notions: 1) that Transition Design projects can benefit from using AI as a tool for enhancing complex thinking and creativity, and 2) that within these processes, it is relevant to deliberately assign people with the tasks that are rendered as inherently human, namely, ethical choice-making. The article presents a future scenario creation workshop carried out with student collaborators and AI collaborants. The AI collaborants, built on the Gem platform within the LLM model Gemini, assisted participants in exploring different dimensions of the STEEPLE framework (social, technological, economic, environmental, political, legislative, ethical) and building possible scenarios. Findings suggest that AI collaborants can be useful to foster exploration of diverse alternatives and can be a means to train students in complex thinking, a key competence for Transition Design. However, issues inherent to LLMs need to be considered, such as narrative style, possible bias or homogenization effects. Finally, optimal interaction modalities with AI collaborants within a participant group need to be explored further.