One of the great archetypes is the reluctant hero. (It's so archetypal there's also a Wikipedia page!)

And there is no hero more reluctant than a supporting NPC.

Transcript

Pagetti Rook: On to the plank wi' ye, ye scurvy rat!
GM: Pete, it's ready. Let me set up the models. The barge is here, and this is the skiff.
C-3PO: Awesome thesaurus!
Luke: And I'm on the end of this paddle pop stick, huh?
R2-D2: Lando! Catch! 17 - yes!
Lando: What?
[SFX]: Poomh! {R2 launches a laser sword through the air from Jabba's barge}
Pagetti Rook: Huh?
[SFX]: whoosh...
C-3PO: Lando??
R2-D2: We know Luke won't use it. You won't use it. Han and Chewie are tied up. Lando's on our side and he's over there.
Luke: Oh god, it's a laser sword. Why did it have to be a laser sword?
R2-D2: Lando can rescue you guys.
Luke: Has he ever used one before?
Lando: No!!
R2-D2: He's got hands.
Luke: For the moment.
Lando: Oh, great.