The Story of Poppy
Poppy is a yordle who has spent her life carrying a hammer that she believes belongs to the Hero of Demacia — a legendary figure she was told would wield the weapon to protect the kingdom from its greatest threat. She has been delivering this hammer for a very long time, searching for the hero it was made for, turning down every suggestion that she might be the hero herself with the sincere insistence that she is just the deliverer.
The hammer is the Hammer of Orlon, a weapon of extraordinary power that has been in Demacian legend for generations. She has defended it against those who would misuse it. She has used it, repeatedly, in ways that demonstrate exactly the kind of power the Hero of Demacia legend describes. She continues to believe she is not the hero. She is not playing modest — she genuinely doesn't see the disconnect between "I am not the hero" and "I just did the thing the hero is supposed to do, again."
She fights for Demacia because she believes in what it stands for, with a directness and sincerity that is characteristic of her in everything. She doesn't have complicated feelings about this; she thinks the kingdom deserves protecting and she is going to protect it until she finds who the hammer belongs to. Her yordle nature gives her a resilience and a stubbornness that serves this mission well. Demacia does not always deserve someone this faithful. It has her regardless.