what happens if you dont have a character when you rebirth in diablo 3?

Leah had a hard time growing up in Caldeum. Adria set up wards around Gillian's residence and departed, leaving the barmaid to care for the infant. Adria escaped with Gillian and the two made their way to Caldeum.

While Aidan became corrupted by Diablo and so became the Dark Wanderer, Tristram fell to the forces of Hell. By Diablo's will, Leah was conceived and born a year later in 1264. Not long after Aidan's 'victory,' he met the witch Adria, who realized that Diablo was influencing the prince.

To this end, when Prince Aidan struck down Diablo in the Tristram Cathedral and bound himself to the soulstone in the hope of containing Diablo's essence, the demon had been given the means to fulfill his plan.

And to do that, he would need a vessel to inhabit. He would become the Prime Evil, combining the essences of the Great Evils into a single form.

While the three Prime Evils had masterminded their exile to Sanctuary, Diablo had taken the plan one step farther. From the outset, Leah was conceived as a host for Diablo.

What happens if you dont have a character when you rebirth in diablo 3?