The Unforgiven II

Sometimes Dean still doesn't know if he did the right thing, in letting Lisa and Ben go, or maybe his only mistake was in ever allowing himself to become involved with them in the first place. It hadn't been fair, he knew, for Lisa to have been the one to pick up the pieces after he'd lost Sam, but she had done. She'd supported him through the hardest thing he'd ever had to face, letting go of Sam and trying to carry on with his life, and words couldn't express how grateful he was to her for that. But then Sam had come back, and he'd left again.

Sure, they'd talked about it, and she'd agreed that it was the right thing for him to do, but it still hadn't been fair on her. Where he was involved nothing in her life was fair, and that was something he couldn't forgive himself for. He put her in danger when he was with her and put her through hell when he was gone. Then in the end he'd almost cost both her and Ben their lives.

That was the final straw, when he realised he couldn't keep doing this to her. So he'd asked Castiel to make both her and Ben forget. Maybe if things had been different, and Castiel had never interfered to bring Sam back, he could have moved on and had a life with her, but now he'd never see what might have been. Even though Lisa would have forgiven him for all the trouble he'd brought her, Dean knew that wasn't something he deserved. Letting Cas erase the memory of the pain he'd already caused wasn't the same as undoing it completely, but at least grief over him wasn't something she'd ever have to feel again.