lift your feet. let the snow slide beneath you. don't worry about your jeans; they will end up wet and torn, and you will have to throw them away, or at least put them where you won't be tempted to wear them again. don't steer.
it doesn't matter that your brother is still at the top of the slope, laughing at you with the fraternal derision that signifies a minor victory. he doesn't get to feel this. the ridges that bluntstab your thighs, flowing over ice and twigs and dirt and dogshit. you are the one who will get to stand up when you get to the bottom, stand up and walk not back up the hill, but further down the slope. leave him behind, he'll have to pussyfoot down and try not to fall. he should have brought the tube like you said.
you'll get back to the car and drink both shares of hot chocolate, and he'll punch you in the arm and it will feel like he did it as hard as he could, even though he'll claim he was holding back. on the drive back he'll play music that you can't sing along to, because that shit's gay. you can still tap along a rhythm on your legs, a wet shoe against his dash. he won't even notice because he'll be busy trying not to crash his miata into a telephone pole, complaining that the windshield wipers freeze over too easily. "they just don't make cars like they used to," even though he was born in 1990. embrace the fact that you were born in 1995, that you've always known the internet, boy band pop, and you got a cell phone when you were 9. they really don't make those like they used to, but you don't have to say that.
pick up his coat from the foyer floor when you walk inside after him, bring it to the dryer machine in the bathroom, and figure out how to use it. you belong to the generation of teaching yourself, and he doesn't even know how to butter his own bread at dinner. maybe he'll live longer, but you'll live happier.