Confused.

Confused? Welcome to Dear Door ╮(￣▽￣)╭
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Sid wiped Jin's(bf) memory to save him/keep him from falling further apart.
Aaron (the doc) used souls to heal Jin's soul which had taken a huge crack because he had been a door - it seems only Joon was able to withstand that, other humans usually get mad from it and die quickly. (There are reasons for that revealed much later.)
With Sid and the demons that's still a "really no idea" to everyone I guess. They control part or all of him, though there's still his real self inside or something like that.

Sid betrayed Cain to Satan? Is that right?

Thank you for the reply.

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Even that is hard to say. Satan went to Sid to bargain him into betraying Cain, but it does not seem as if he was really working with Satan or doing whatever Satan actually wanted of him to do.
It's so hard to tell because parts of Sid seem to want one thing while other's want something else. The one thing that should always be taken into consideration when thinking about whether Sid is actually really betraying Cain is the fact, that Sid had several chances to disposed of both Cain and Joon. The very first he had in chapter 3. He just never ever did kill either of them even when he could - and he tells Ben to protect Cain.