Species don’t exist in isolation—they constantly interact with one another in ways that range from mutualistic to antagonistic, shaping ecosystems and evolution. These interactions aren’t fixed; they shift with changing biotic and abiotic conditions, making their outcomes challenging to predict. My dissertation explores how temperature, predators, and plant rewards mediate species interactions across multiple trophic levels. Through experimental studies on indirect defense mutualisms, fungal microbiome dynamics, and pollinator communities, I examine how ecological context shapes the functioning and outcomes of plant multitrophic interactions. As climate change and biodiversity loss reshape species interactions, understanding the relationships between these diverse groups is all the more important.