Board Thread:Episode Discussion/@comment-24993958-20170114144645/@comment-4010415-20170115130022

Well... as was pointed out to me by NeoVelociraptorDelta... Salem's "ring" is actually some kind of Grimm bug, which Phantomlink says appears to be a tick.

A tick is a parasite.

Perhaps the Grimm tick on Salem's finger is actually Salem herself, possessing - and eventually corrupting the body of - a human host.