Loser Has Your Back

""When you first came to CTU, I never thought it was going to be you that was going to cover my back all those years.""

- Jack Bauer, to Chloe, Series Finale of 24

""Cavalry's here. Cavalry's a scared guy with a rock, but he's here.""

- Xander, to Buffy, Season 2 finale of Buffy the Vampire Slayer.

It's all come down to this. The quest is almost over. One by one, the people on the quest have dropped out, died, or been magically transformed into trees. The final battle is approaching. The Hero turns to see the who is left at his side, only to find... Bob, the Mostly Incompetent Comic Relief Sidekick?

Yes, somehow, the rookie, the Plucky Comic Relief, the Butt Monkey, The Load, the Mauve Shirt, the... well, you get the idea... is the only person who still has the hero's back. This happens most frequently in a Dwindling Party situation. Expect the hero to say "I never thought you'd be the one to have my back". Alternately, the Hero wangsts that he has been left all alone, so that Bob can remind him that he's still there. Frequently include Crowning Moments of Heartwarming.

A common variant on this comes when members of a police squad, any type of procedural, military band, or True Companions have been replaced for one reason or another over the course of an entire series. Towards the end, especially in the finale, the hero and the last remaining member of the original band reminisce about how things have changed. In particularly grim versions, everyone else is dead, and the Hero wonders how Bob is the only other survivor.

Sometimes its the first step on Bob's road to being a Badass. May also result in the side character getting dangerous.

Anime and Manga

 * Happens in Dragonball Z during the battle against Super Bu: Gotenks and Piccolo were assimilated, and Goku planned to use the Potara earrins with his son Gohan but he too was absorbed. At that point he realizes that the only man left for a potara fusion is Mr Satan.

Fan Works

 * Parodied in the Dragon Ball Fan Fiction Dragon Ball Insanity School: After Goku's getting seriously damaged by Baby he asks for some help, and Pan quickly promise to help him. Beat. Goku re-asks for some decent help.

Film

 * In Judge Dredd, in the final fight it's Fergee, the petty criminal and con man whom Dredd has been treating like garbage all through the film, who disables Judge Rico's Combat Bot, saving both Dredd and Hershey's lives.
 * In The Fifth Element, effeminate radio host Ruby Rhod is the only person protagonist Corben Dallas can count on during the pitched gun battle.

Literature

 * Rowan of Rin: The first book ends with Rowan being surprised that Alan, the 'useless' baker, is the last man on the quest except Rowan himself. In fact, the questing party pretty much dissolved in reverse order of powerfulness.
 * An abbreviated version of this occurs in final battle in Harry Potter and the Order of the Phoenix. In the epic climax, the kids go down pretty much in the reverse order you'd expect (Hermione, Ron, Ginny, Luna...), ending with Neville, who up until then had been the series' Butt Monkey, as the last man at Harry's side. Its the first indication that Neville isn't as hopeless as he seems, and the first step in Neville's ascension to utter badassery.

Live-Action TV
"Glory: You lost your hammer, sweetcheeks. What're you gonna hit me with now? (a wrecking ball comes out nowhere to knock Glory through a brick wall) Buffy: Whatever's handy... Xander: (shown to be at the wheel of the crane attached to the wrecking ball) And the glorified brick-layer picks up a spare..."
 * 24 gives Jack Bauer a particularly awesome one of these. He and Chloe are the oldest remaining members of the CTU, and one of the last lines of the entire series is Jack telling Chloe that he never thought she'd make it to the end.
 * In the Doctor Who episode "The Pandorica Opens", The Doctor has a revived, Roman robot Rory backing him up. And it works.
 * Buffy the Vampire Slayer, episode "The Gift": In a massive fight taking place at a construction site, all of the rest of Buffy's allies have been sidelined, Buffy's been deprived of her weapon, and the Hell-God Glory is bearing down on her, fully capable of tearing Buffy's arms off and feeding them to her:

Theatre

 * Older Than Steam: In the morality play Everyman the title character is abandoned by Beauty, Strength, Discretion and Five Wits. The only one standing by Everyman when he goes to be judged is Good Deeds.

Video Games

 * Kinda what happens in the bad ending of Mass Effect 2, though not to Shepard but to the Illusive Man: if you really, really screw up the Suicide Mission, Joker (who is not a loser but he is no fighter, either) is the only Normandy crew member that Cerberus ends up with for the upcoming battle against the Reapers.
 * Even in a normal ending, Joker helps out by standing at the ship's outer door with an assault rifle and covering Shepard and co. as they run back to the Normandy. For most players, it's probably the last thing they'd expect to see someone with brittle bone disease doing (even in light of Cerberus springing for some proper medical treatment).

Web Comics

 * Happens to Sheilla Horowitz in Knights of the Dinner Table during the "Grudge Match" arc. Following the elimination games, one member of each of the gaming groups is supposed to belly up to the table for the final showdown. Sheila expects to be backed up by the power players from the other 'evil' groups: the other players being supposed to take the fall to allow them to progress. Instead she finds herself Surrounded by Idiots.

Western Animation

 * In the Goofy cartoon "Double Dribble", a basketball team keeps losing players until the only one left is a pipsqueak who is only knee-high to the others. Surprisingly (or not) he wins the game.