Mario groaned as Luigi grasped his throbbing manhood and began rubbing and massaging it. "Bro... So good... Luigi, a-ah! C-Cold!" The older moaned loudly as he felt two cold fingers penetrate his entrance, and he clutched onto his brother desperately. "Mario, I need you..." Luigi whispered softly in a begging tone of voice, thrusting his fingers in and out of his brother at a fast pace. "You can have me!" Mario managed to choke out, clinging onto Luigi tightly and nibbling his collarbone. "M-Mario... Ah...! Fuck...!" Luigi groaned softly and pulled his fingers out as he felt his brother's teeth sharpen and sink into his neck. He quickly thrust into the older, earning a long, loud, and low groan from the other. "Luigi, ah Fuck... So big...!" The older gasped. Large brown wolf ears sprouted from his head and a fluffy brown tail grew from just above his rear, while Luigi's teeth had sharpened and grown into large fangs and his eyes changed from blue to blood red. "M-Mario... Y-You're s-so... Nnff... fucking tight...!" The younger groaned, thrusting in and out of his brother at a quick pace. "Luigi! Luigi, oh! F-Fuck yes , h-harder! Harder, right there!" Mario gasped when his brother hit that one spot. "You're so beautiful when you're like this, my dear, sweet Mario..." The younger breathed into his brother's neck, close to cumming. "I'm going to... To...! G-Going to...! Mario, I'm cumming!" Luigi moaned loudly, shooting his semen deep inside of his brother. "Luigi , oh fuck...! So much c-cum! Feels s-so good!" Mario moaned, panting heavily. Luigi took the chance and sank his fangs into Mario's neck, injecting him venom into his brother. "L-Luigi...!" Mario gasped, shaking. Luigi clutched onto his brother, forcing him to pull away. He licked his brother's blood off his lips, shivering slightly at the delicious taste. "Luigi, what have you done...?" Mario groaned in pain. Luigi hugged him closely, instantly feeling bad... "It hurts..." The older whimpered, clinging onto his brother and shaking