Downplayed: Bob has always been a stoic sort of person, and when he sees Alice die, he sheds a Single Tear.
Bob is a Reality Warper, whose powers are tied to his emotions. he maintains his stoicism, lest he harm those around him, but when the big bad kills Alice, he goes on a Roaring Rampage of Revenge, powers and all.
Inverted: Bob is a highly emotional man, most of the time, but after seeing Alice die he is stone cold stoic.
Subverted: Bob sees Alice die, and it looks like he might betray some feeling, but it doesn't come.
Double Subverted: Until he's alone.
Parodied: Bob gets slapped in the face, a bucket of paint dumped on him, is involved in a car crash, and yet never shows emotion, until Alice knocks his coffee out of his hand. At which point he lets out a Big "NO!"
Zig Zagged: Bob seems to be about to show emotion after Alice dies, but he holds it in. When he's alone tries to let the tears flow but still they don't come, but the next time he's with his companions, the water works open up.
Averted: Bob, stone-faced as ever tries to save Alice from her horrible fate, but cannot. Even after this, his face shows no emotion, and his voice wavers not at all.
Enforced: "Bob's seeming lack of emotion is driving viewers away. We need to show that he does have feelings and he does care."
Lampshaded: "Wait, I thought Bob didn't have feelings."
Invoked: Knowing that Alice is the person Bob cares about most, the Big Bad arranges for her to die in front of him, while he can do nothing about it.
Exploited: During Bob's moment of emotion, the enemy attacks and defeats him.