Despite being named Agent J's new partner in Men In Black, Linda Fiorentino's Agent L was completely omitted from Men In Black 2. Throughout the first movie, Agent L was established as smart, capable, and wholly uninterested in "normal" people. She makes for the perfect Men In Black agent, and following Agent K's retirement at the end of Men In Black she steps in as Agent J's new partner, seemingly primed for a major role in any future adventures.

https://screenrant.com/men-in-black-agent-l-what-happened-sequel/