One of my very favorite Spike scenes is one that no one ever talks about. It's in "The Weight of the World," when Willow sends Spike to check on Glory's apartment. Now, remember that just a couple of episodes ago, Glory tortured Spike within an inch of his unlife, and the episode prior, Glory wiped the floor with the whole gang. Spike knows he has absolutely no chance in a solo fight with Glory. If she catches him again, she will simply rip him to pieces.
Now, if Angel were cast in a scene like this -- or if Buffy were, for that matter -- they would march in there without the slightest hint of fear or hesitation, because they're Heroes(TM). But Spike is shown to be terrified; he flinches when he thinks he sees/hears something in the apartment. He could easily have just turned around and skived off, or he could have not gone to the apartment in the first place, and gone back and told Willow that he couldn't find anything. But here's the thing: he goes in anyway. You see him literally assume the Big Bad armor and go investigate.
It's not for anyone else's benefit; no one else is there. To me, that scene is pure Essence of Spike, and it's a huge part of why I love the character.
