Bruce stood there, as Damon offered Enigma his bleeding wrist, and watched as Enigma accepted it. He was alright up until the point where Enigma began to get closer to Damon than Bruce was comfortable with.
He didn't want to interrupt just yet, as he wanted enigma to benefit from the blood she was getting, but he certainly didn't approve of his finances behavior.
Bruce was aware that Damon had Elena, but he wasn't exactly sure if that would stop Enigma from pushing any limits. Bruce would rip Damon apart if he wasn't smart enough to back off when Enigma began to push.
Patiently, he waited, despite the scene unfolding before his eyes.