"I believe there is a possibility of knowing," Cas replied, nodding. "There is a Heaven here. Like the one from my world, it is likely war torn, but the Heavens of the individuals who went there should likely be intact. Heaven is universal. And I would like to look."
Castiel meant that. Had John and Mary Winchester been in Heaven at the time, he would have looked for them to reassure Sam and Dean. It was one of the few things he could do to create hope or relief within the human species. It felt right. So rarely did he get the opportunity to do anything good anymore.
"She clearly meant a lot to you. I would like for you to know if she is all right or not."
Cas would never get to know himself if Anna was all right. There was no Heaven or Hell for angels. But there was for humans at least. "With your permission, I will look."