Parodied: Lance is a literal lance wielded by Hiro and they spend more time arguing with each other over petty things than fighting evil.
Zig Zagged: Hiro starts off as The Leader while Lance is the second-in-command. Hiro is cool and calm while Lance is snarky and violent. Due to personal issues, Hiro steps down due to the pressure of leadership and allows Lance the position of the leader. The new sense of responsibility makes Lance mature while Hiro grows violent and snarky now that he doesn't have The Chains Of Command weighing him down. Lance's bloodknight persona forms a Split Personality Take Over which forces Hiro to resume leadership; this immediately calms him down and he reigns in the new lance who becomes his Devil's Advocate.
Percius felt that Hiro needed a Yin to his Yang, and thus recruited Lance.
Immediately after Hiro, Tony, Will, and Chica form a team, they go out looking for Hiro's perfect foil.
Exploited: At the tryouts, Lance acts the opposite way Hiro would because he believes this will secure him the position.
Defied: Lance finds out he was chosen simply to compliment Hiro's skill set, flips out, and quits.
Discussed: "Hiro and Lance are 100% opposite, right down to their favorite colors." "Yeah, it's like they planned it."
Conversed: "They sure have a second-in-command and the leader bicker every episode due to the differences."
Lance grows tired of always having to play second-fiddle to Hiro, so he goes solo.
Lance is clearly out-gunned on every front: not as powerful as Tony, not as smart as Will, not so morally or emotionally grounded as Chica, and he doesn't quite have have Hiro's natural leadership ability. He develops psychological issues over his inability to stand out in The Team, which eventually leads to him trying to take on one of the other roles when he's not quite cut out for it.
Lance is feeling underappreciated so the Big Good puts him through a Peggy Sue to show him that The Team is more helpless than he thought.
Lance is comfortable in his role because he is a better fighter than Will, both faster and smarter than Tony, doesn't have the whole team relying on him emotionally like Chica, and if a plot fails, it's on Hiro's head, not Lance's. His responsibilities are more suited to his nature even if his personality sometimes clashes with Hiro's, they're the best of friends and Hiro relies on Lance both in the heat of battle and in their lives outside of it.