Angel might be enraged, but he’s still the Master Vampire, and some dangerous enemy is enough to keep him thinking,
strategizing rather than entertaining stupid thoughts of merely running in and tearing the body apart, because being intelligent might just keep him alive.
Or, well, the closest equivalent any vampire can come. So while the demon is screaming, calling for blood and pain, he ignores it, remaining careful in the face of this grinning opponent.
Despite his reputation as the Scourge of Europe, Angelus rarely picked a fight he couldn’t win, so he’d had much less experience fighting strong opponents.
Souled Angel had a bit more, since meeting Buffy, since setting up in the Hyperion, helping the helpless, but he’d usually had backup or some other type of assurance,
not just running into a fight blindly.
It’s rare that he actually wishes Spike was here to back him up, but this is one place where Spike’s experience would be handy to have around.
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