A noticeable surge in students' widespread adoption of ChatGPT in the past year brought attention to the need for a deeper understanding of their interactions with this new technology. While attempts at theorising learner-ChatGPT interactions have been made, few studies offer empirical accounts of the interactions between learners and ChatGPT. This study aims to address this gap by utilising Emirbayer and Mische's Choral Triad of Agency as an analytical framework to investigate secondary school students' self-initiated interactions with ChatGPT in the context of historical inquiry. Through an in-depth examination of three cases, we unpacked three distinct types of learner-ChatGPT interactions--ChatGPT-as-historical source, ChatGPT-as-feedback, and principled non-use. Although students presented unique interaction patterns with ChatGPT, each case was found to have limited routined interactions with ChatGPT. Our analysis revealed that the students held static agentic orientations in their use of ChatGPT due to their limited experiences with ChatGPT and inadequate ideation for alternative ways of utilising it. Implications of this study propose the need for deliberate interventions to encourage students to have more diverse and meaningful interactions with ChatGPT.