Sam was saying yes to Lucifer. He made up his mind, and there was no changing it. Dean had set off to go find Sam and Adam before things could escalate. He told you, Bobby, and Cas to stay behind, but of course none of you listened. You weren't just going to let him get himself killed.

Cas had ended up throwing a Molotov at Adam in order to give Dean time alone with 'Sam.' That only resulted in Cas being detonated by Lucifer. Bobby would be the next go in, giving you a look that said 'Stay here.' You listened.

"Sammy, can you hear me?" Dean asked, walking closer to Sam.

Lucifer had already taken over. Sam was barely present, if at all. "You know... I tried to be nice... for Sammy's sake." He sneered, approaching Dean. "But you... are such a pain... in my ass."

Lucifer threw Dean onto the Impala, subsequently shattering the windshield. Everything in you wanted to get involved, but you didn't. Bobby shot Lucifer in the back. With a smirk on his face he spun around. He turned his hand and snapped Bobby's neck. He dropped. Dead. You covered your mouth.

Dean managed to choke out a 'No!'

Lucifer smiled, proudly. "Yes." He tore Dean off the Impala and threw him against it.

"Sammy? Are you in there?" Dean asked, still dazed and rattled from the impact.

"Oh, he's in here, all right." Lucifer landed a punch. "And he's gonna feel the snap of your bones." He leaned in closer and smiled sadistically, landing another blow. "Every single one." He yanked Dean up and shook his head. "We're gonna take our time."

As Lucifer went to throw more punches at the already bruised, battered, and bloodied Dean, you knew this was it. You had to get involved. You didn't have a choice. Screw what Bobby wanted. Screw what Dean asked of you. You'd end this.