The Story of Bard
Bard is not a being that has a biography in the conventional sense. He is ancient — older than Runeterra's current civilizations, possibly older than Runeterra itself — and he moves through the world on a purpose that he does not explain because the explanation requires a framework that mortals don't have. Meeps follow him. Chimes mark his passage. He collects things that he considers cosmically significant, which may or may not include the things mortals consider significant.
He has intervened in mortal affairs on several documented occasions, always at moments that seem arbitrary from the outside and which, in retrospect, turn out to have prevented something catastrophic that the people involved didn't know was coming. He does not explain these interventions. He communicates primarily through sounds — not quite music, not quite language — that carry emotional meaning without semantic content. People near him often report knowing what he wants without being able to say how they know.
The most coherent theory is that he maintains something — a cosmic balance, a set of wards against threats that Runeterra doesn't have names for — and that his wandering is the maintenance, and the items he collects are the tools, and the whole vast project is so far above the scale of normal human concern that explaining it would be like explaining ocean currents to a fish. Whether this is accurate is impossible to verify. He continues regardless, untroubled by the mystery he presents to everyone he meets.