u/ElderGodFujin

If you romance Minthara, there's dialogue between her and Gale where Gale says he found an empty bottle of venom in camp and asks if it's hers.

Apparently, in preparation for you ever visiting Menzoberranzan together, she has been steadily dosing you with venom, in your sleep, to build your immunity.

Gale's reaction? "Let's never speak of this again."