Anakin and Obi-Wan fought through the base and out onto the structures built across the river of lava. Anakin fought, fueled by jealousy, rage, and hatred. Obi-Wan fought, fueled by his love for Padmé, his grief for the lost Jedi, and his desire to protect the Republic and all the people it represented.
The fight was close, since both knew the other's style and weaknesses. But taking advantage of Anakin overextending in anger, Obi-Wan managed to disarm Anakin and Force-push him off the edge of the bridge. Concerned, Obi-Wan watched him fall into the lava, a dark spot flaming in the flow of molten rock. Pained, Obi-Wan picked up Anakin's lightsaber and returned to the ship.
"Anakin?" Padmé asked.
"I'm sorry," Obi-Wan said.
Padmé went into another contraction, alerting Obi-Wan to her condition, and they sped back to Senator Organa's base. She didn't make it, though, and Obi-Wan delivered both her children in the ship. He washed them and wrapped Leia in a spare blanket, and put Luke in his own tunic.
"I guess Anakin was wrong," she said, gazing at her babies.
"About what?"
Padmé closed her eyes in pain. "The whole reason why he joined Palpatine was because he'd dreamt I died in childbirth. His goal was to save me."
"It wasn't his only goal. If it were, he would have forced Palpatine to tell him the secret he desired, and he would have gladly lived with you on some forsaken rock, raising his children."
"I guess you're right."
Padmé fed them and fell asleep with Leia, while Obi-Wan flew the ship with Luke in his lap.