Dean wishes - he wishes Sam was wired differently, some days; he wants Sam to understand, with a desperation he refuses to even admit to himself, that the lies, the secrets, all of it - it was for Sam's own good, it was for Sam that they took the time to keep his mind off the danger Dad went and faced every single day.
But Sam isn't wired differently - he worries, persistently, and takes it as betrayal when someone lies to him, and he just - he takes things so to heart.
It hurts Dean, deep inside, even as he keeps it casual, keeps it light, tries to play it off - it hurts to know Sam has lost trust in people a long time ago, underneath floppy hair and too bright eyes, too small a face, and that Dean contributed to that loss.
Fill: Supernatural, Dean & Sam, The Secrets (and lies) We Tell
But Sam isn't wired differently - he worries, persistently, and takes it as betrayal when someone lies to him, and he just - he takes things so to heart.
It hurts Dean, deep inside, even as he keeps it casual, keeps it light, tries to play it off - it hurts to know Sam has lost trust in people a long time ago, underneath floppy hair and too bright eyes, too small a face, and that Dean contributed to that loss.