User blog comment:DaNASCAT/Technical Update: May 6, 2015/@comment-24654044-20150508112550/@comment-452-20150511155342

One way is to link to Thread:837795.

The "?permalink=837795#comm-837795" part of that URL reveals that the page id of your comment is "837795" and threads are addressed by page id, so any valid page id can be linked by "thread:".

In my opinion, this behaviour should be changed so that "thread:" links to non-parent-threads should be detected and redirected to the normal url for that page. I've reported this to Wikia Staff, but even a casual analysis of the functionality of the "thread:" system would have revealed this before development even started, so this is clearly something they were aware of from the beginning so there is no reason for them to "fix" it.