Dean couldn't missed the flicker of dark anger across Seamus's face. He knew Seamus had to suspect, if he didn't know for certain by now, that his mother was gone. There's no way Dean would have come back without her, if she'd still been alive. He couldn't bring himself to confirm it or to ask if Seamus already knew, especially not after that heart-rending little statement Seamus made.
Dean instinctively tried to move his right hand and his eyes went shiny when it didn't move. So instead he struggled to twitch his left, which responded, though sluggishly due to his medication. "Always, my love. I'll always come back."
He exhaled slowly and tried to answer Seamus's other questions. "I had to wait...until she got distracted, overconfident. Hit her with a lamp. Knocked her out I think. Flooed home. Passed out I think, then Flooed here."
Dean frowned. "She took me because I recognised her." Forming the full sentence took effort, but it was necessary. "She saw that I recognised her."