Emmett had been afraid to take too much in general, true. He still had issues with taking too many blood bags. After all, Roman might need them. or someone else and...he'd always hated taking more than he absolutely needed to stay alive. It felt wrong somehow, as a human too.
That said, he did want to do well, and since Damon was watching, resigned himself to the events, and stared at Diego as he pulled him around.
"You want me to suck on your neck." He said, and got a weird look from the other. "You want to let me feed from you. I'm sorry." he added quickly, "But...you have to."
Probably not the easy way to get that done, no. "I uh, won't hurt you."