Apparently tieflings have above average body temperature, and it’s currently autumn according to Matt in the last episode of Critical Role so it’s only going to get colder from here. Which means the resident disaster tieflings need to use their natural abilities to keep the rest of the Mighty Nein warm with hugs and cuddles. If somebody gets especially cold, they’ll sandwich that person between the two of them to warm that person up fast. They’re just doing their part for the team and it has nothing to do with the fact that Molly and Jester are a couple of physically affectionate marshmallows who will take any excuse to cuddle.