I am looking to see if it is possible to embed a topic on my discourse site in another topic. Say last post as a live comment thread.
Ie similar to a news site where there is a comment section. In my use case an author posts a blog; they are the only one that can post in main topic. Last page of Article serves up a custom iframe comments from another category topic. As users are in the same site they can use the iframe to reply directly to comment thread
Did you take a look at the Journal Plugin?
Yes But I am looking at a different idea. As we can embed a discourse topic as comments in another site. In theory we should be able to embed a topic as comments in a discourse topic. With maybe just using a theme component maybe.
I have completed a staruc iframe test. It works - however it embeds the whole site with header and footer in my case in mobile the f have component.
So My thought is maybe the embed js code might be able to be adapted with a tailored iframe added to a topic as comments on final post in a topic.
Benefit potentially no plugin required expanding usability to any discourse site via simple TC. Well maybe not that simple. 
The other benefit over journal and post voting is that a member could goto to the full comment topic or just view from Article topic
Though a Plugin could likely have some overrides for a special comment category to restrict post/comment length and other goodies But maybe not needed.
I should have maybe clarified in the Op that I am aware of both Journal plugin & post voting.
Hmm… maybe a target to remove the header and sidebar when in an iframe using CSS? Maybe something like (not sure if that’ll work)
iframe > html > body > ... {
display: none;
}
I’ll see if I can get it to work, maybe with some JS 
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@Heliosurge how would you get it to embed it on topics, if there are multiple topics? If I understand correctly, each blog topic is linked to the respective comments topic, in a seperate category. Just curious 
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Why not perhaps uncheck the ‘Create’ permission for those who aren’t blog writers, but leave the ‘Reply’ permission checked, and for blog writers the ‘Create’ checked?
Yes each blog topic would have a comment topic in another category/sub category.
I am wondering though if a similar ko Nd of iframe idea might work. To create maybe a div that will display a topic within a box. More or less a kind of iframe. Similar to how we can use CSS and TC to influence how a category displays.
Category permissions in this regard the blog topic would be similar to Moon’s suggestion of the journal plugin. Only the Author can post & reply in the Article category. The comments say in the final post would be an element showing window to comments in an interactive iframe idea.
Alternatively could likely just use code similar to serving discourse comments on something like ghost blog. But I think it could likely be made to look & work similar to media sites with comments section.
Okay Think I may have found a post with some code that may help to achieve this with some modification. Maybe converting it to a bbcode wrap?
Theme component Right side Blocks also has some code for recent replies may also work.
Basis to modify to a bbcode wrap that will maybe use topic I’d as a variable to fetch topic in box to display in a post.
Have it’s own header at top of box with link Add comment. And have first post display none.
Other potential application beyond adding a comment window. If doing a single post. One could also say use it in an announcement only category to display a pill or other such things.
In the course of my experimentations along similar lines I learned a lot and got some new ideas by studying @sylque ‘s discpage plugin…
Yep that is a pretty cool plugin but I am thinking we could have a scrollable contents in a topic.
Your demonstration looks quite promising. If we can do a TC it also makes it more accessible regardless of hosting type for the most part.
Right side bar blocks has code for recent replies. That might also be useful. More ways we can duplicate or mimic features in other platforms the more diverse Discourse will be seen