Does the contract have more power when it is visible Or cannot be used when covered? There are a few times like in ch82 where O!Ciel calls Seb and rips off the eye patch but then quickly puts it back on. Also, in ch93&95 do you think it was Seb who was giving him the visions of his brother to try and pull him back to reality? He was there both times and it seems like he talks with him directly the second time. Seb also specifically takes off the eye covering in 94. Perhaps he knew he'd need it?
The contract seal might have the most power when visible, but it definitely works without being uncovered. I think a lot of this eyepatch removal when giving some orders is mostly for dramatic effect. So far, it has only happened when it doesn’t matter who sees it; those witnesses are about to die anyway, right? With one notable exception!
But it’s possible that, at some point, the eyepatch will be off in front of people who didn’t know about the contract... and might live to tell tales about it later... when it no longer matters who knows. Perhaps our earl or another character will make some huge reveal (to other characters) about the nature of the contract between our earl and his butler. I would expect Sebastian to reveal the seal on his left hand, too.
Until then, we will only see Sebastian’s seal when he’s also not needing to hide it. Just like with the eyepatch, the only major exception has been Sieglinde; she’s seen both seals. William has seen Sebastian’s seal, too, but he’s a reaper and fully aware of what Sebastian is, so he hardly even counts. Seeing the seal on the back of Sebastian’s hand is probably the only thing that keeps William from trying to kill him right away; he knows the demon is “collared”.
No, I don’t think Sebastian is actively giving our earl visions of real Ciel to speak with about feelings of guilt, etc. Particularly since real Ciel talks about Sebastian in a negative manner. The only way Sebastian might be involved with that scene is because he’s already devoured real Ciel’s soul. If Sebastian’s in the vicinity, and if our earl is in an unconscious or subconscious state of mind, it might be possible for the twins’ souls to interact with each other. I have a same feeling that something similar happens later, in ch108, when our earl is asleep and thinks he’s woken up to Undertaker having him drink something, but then he actually wakes up... to find Sebastian. This all ties in nicely with Mother3 theory, since the mirror twin brothers in the game (Claus and Lucas) make psychic connections to each other a few times, even though the older mirror twin is also dead and reanimated (a Fascinating Chimera).











