Loving Dean Winchester never had been an easy task. There were times when Castiel just wanted to raise his hands to the sky and shout all his anger away. But he never did, because that would mean to leave Dean and he couldn't. He was bound to this strange creature of his Father, he had been the day Castiel first took sight of him. It wasn't in Hell, when Castiel had found him, torn, bloody and miserable. He fell in love with him when he stood at his crib and looked down on the tiny human in front of him. Dean had been asleep, peaceful then and knew nothing about the things he would have to go through for Heaven itself. He knew nothing of his tasks and Castiel had been thankful because he felt sorry for him. He felt truly sorry. Castiel never had felt anything and Dean moved him, moved things in him Castiel didn't know of. At first, it had scared him because angels weren't made to feel, they were soldiers and had no right to judge by feeling.
Yes, Castiel was scared, even now, when he looked at Dean and felt, just felt. Glad, in love, despaired, scared, hopeful and oh so alive. All of this crashed right down on him when Dean held him close, when he kissed him, when he nuzzled his dark hair. Castiel knew he would never feel that alive again because their love had a dead line. They both knew but they never said a word about it. There was no reason to destroy the peace that captured their pounding hearts and let them rest, even if it was only for a few moments. So instead they clung to each other, as long as they could before Heaven or Hell drew them apart again.
Castiel lost his old life due to Dean, but he gained a new one. 'A better one', he told Dean, when the man who went to Hell for his brother, who had fought against angels and demons, kneed in front of him, his head buried in Castiel's lap, sobbing and asking for forgiveness because he had Cas made fall.
'You know, Dean Winchester, it's not easy to love you. But it doesn't matter because you're worth every struggle and every fight. So I love you and always will.'