Robin (Cobie Smulders) had a habit of yelling at Patrice in the final handful of How I Met Your Mother seasons, but the reason behind the hatred for her co-worker was never fully explained. The recurring figure, played by Ellen D. Williams, first joined the sitcom in season 7 before serving as a thorn in Robin's side for the remainder of the series. Their complicated friendship became an often used gag, seeing as Robin would tend to freak out on Patrice any time the woman did something kind-hearted.
Patrice made her How I Met Your Mother debut in the episode titled "The Stinson Missile Crisis." She worked as an employee at World Wide News alongside Robin and Barney's love interest at the time, Nora. While Patrice viewed both women as close friends, the feelings weren't mutual on Robin's end. Despite the fact that Robin always screamed at the woman for butting into her life, Patrice never backed down when it came to helping her co-worker.
When Robin did get angry at Patrice, which was a normal occurrence, she usually used the phrase, "NOBODY ASKED YOU, PATRICE." Seeing as Patrice was introduced around the time that Barney shifted focus to Nora, Robin's hatred could have stemmed from jealousy. Since Robin elected not to lash out on Nora, she chose another target with the innocent Patrice. There was also another possible explanation for Robin's behavior towards Patrice, and it had to do with their opposing traits.
Robin didn't have the most loving childhood while growing up in Canada due to the lack of a relationship with her parents. Patrice, coincidentally, had a very caring, matriarchial demeanor, which Robin wasn't used to. For a brief time, Patrice even invited Robin to stay in her apartment, but the latter viewed it like she was being smothered. Essentially, Robin couldn't handle the kindness and enthusiastic personality of Patrice considering she used her own standoffishness as a defense mechanism.
Differing personalities aside, Robin's distaste to Patrice's presence served as an opportunity to expand the running gag in How I Met Your Mother's later seasons. Robin's anger shielded her from realizing that Patrice was only pretending to date Barney in season 8 as part of the Playbook's ultimate play, "The Robin." Even though the woman helped get Barney and Robin back together, she wasn't even invited to the latter's bachelorette party. Patrice clearly felt the need to show up anyway, which provided more humor and opportunities for a few more Robin outbursts. Robin seemingly lightened up when it came to Patrice since she allowed her to be a bridesmaid at her wedding. That said, the show revealed that Patrice left World Wide News to be a radio talk show host, and Robin served as a regular caller despite freaking out when she got interrupted.