He decides to make a jump that could have killed him. For example.
And how did that develop/change the character? It is just another act of recklessness…
I’ll add to Mala’s point and say I don’t think he saw it as a fall that could have killed him. I think from the look of resignation on his face, he saw it as a fall he knew would kill him. I think it’s significant character development. He sees only two ways out: death or give in to Vader. It’s subtle in its execution (to the audience) but it’s far from the reckless kid we met in Star Wars. He’s willing (and attempts) to make the ultimate sacrifice to beat Vader and he makes peace with that decision. Nowhere near reckless.
- edit - What Alderaan said.