Although it was a subtle gesture, Emma was seen sporting a pin in support of Planned Parenthood, while other stars in the red carpet wore blue ribbons in honour of the ACLU.
Ryan, 36, and his older sister caused quote a commotion before everyone figured out she was actually the actor's blood relative.
Gosling and longtime girlfriend Mendes are parents to two young children, but we are used to seeing Ryan solo at Hollywood events.
In short order, "Ryan Gosling Oscar date" became a trending google search, and news outlets like Refinery29 asked, "Who is the mystery woman sitting next to Ryan Gosling?" To head to the Oscars in honor of the night's most nominated film, La La Land, Gosling selected a Gucci tuxedo with charm befitting the star of a movie musical.
Gosling and Mendes, 42, have been together since meeting on the set of 2012's The Place Beyond the Pines. Normally very private about their relationship, Gosling very publicly thanked Mendes in his recent Golden Globes acceptance speech when he won for his performance in "La La Land". "To my daughters, Amada and Esmeralda, I love you".
And the award for best brother of the year is.
This was the father-of-two's second Academy Award nomination.