Online discussions have emerged as one of the most popular practices of writing in academic contexts in the twenty-first century. Nevertheless, we know little about the rhetorical features and composition strategies employed by multilingual writers in these types of discussions. Using online discussions in the brainstorming phase of the process of writing a persuasive essay, this study inquired into the argumentative strategies employed by two multilingual writers when transitioning from one academic context to the other. A functional approach was utilized to analyze the discursive choices made by the two multilingual writers in online discussion posts and comments as well as the final versions of their essays. Findings reveal that while both multilingual writers successfully tackled the language demands of online discussions and persuasive essays through experimenting with a diverse array of discursive markers, they used different argumentative strategies to construct, strengthen, and position their ideas across the two academic contexts. This difference demonstrates the two multilingual writers' ability to tap into their linguistic repertoires to creatively make discursive choices according to the demands of each academic context. Implications include the use of asynchronous, written online discussions as a springboard for multilingual writers to first argue ideas with an audience of peers to then select the strongest positions when writing more linguistically demanding pieces such as essays.