Drinking/drunk headcanon: Regina is constantly determined to get Maleficent drunk. She knows this is the only time Maleficent will be honest with her and she knows Maleficent can’t handle her whiskey as well. 

However, if she gets drunk, she often becomes very aggressive and passionate. This often ends in her trying to get Maleficent to kiss her. She isn’t often successful, but if she is, it makes her very conflicted. And, she is still trying to put together the pieces after she woke up one time in bed with Maleficent saying, “What the hell? Get out.”