FASA Games, Inc.

I'll apologize if this was covered heavily on the old forum, or if I colossally missed an obvious rule, but my question is this:

Can an adept weave threads to another person against their will? A rule I read indicated that adepts cannot unweave/sever a thread created by another, and optional rules indicate an adept can opt to unweave their own threads to be able to weave to another pattern item/group/etc. but I can't find rules surrounding the specific scenario I want to investigate.

Here's the situation I'm trying to accomplish within the scope of the rules of magic in ED:
A powerful Theran Nethermancer has "marked" a PC he'd used as a living grimoire (spells tattooed on his body) in the backstory and is using a thread/blood magic/mark of some kind to track the PC's physical location.

As long as you have someone's pattern item (you always need one for a pattern thread) and the relevant Key Knowledges, you can weave pattern threads and use these against the target, whether they like it or not. And you can't directly destroy someone else's thread to you.
You can, sometimes, do so indirectly. This is usually by destroying the pattern item that allows the thread or by "overriding" the thread by weaving a higher-ranked one yourself (usually on threaded items, this is where their "Maximum Threads" comes in).

Given the scenario you describe, an additional comment:
Your usual "locate person" magic in ED doesn't require threads, usually an item associated with the person is enough (Direction Arrow, Direction Sense) and sometimes just having examined it (the Nethermancer's Bone Compass talent).
A spell placed on the target might do the trick too, but can be more easily be discovered and dispelled.

Yes, but remember, you can't weave a thread to your own pattern item because it's pattern is your pattern.

The Werefrog think this needs to be clarified before the PC tries to think of it. Another party member, though, could weave the necessary threads to your pattern item.

Which requires that ally to have the pattern item -- and if that is the case, you probably don't need to worry about an enemy having it.

Weaving to your own pattern items wasn't allowed in ED1, this was a change that only is in the second edition of the game.

The reason you cannot weave to your own pattern items is because pattern magic is basically using one True Pattern to strengthen/support/reinforce another. It requires two True Patterns to work. Weaving through your own pattern items only involves one True Pattern.

A second edition, I would note, that the license was pulled from very quickly. LRG didn't do any major bug fixes, yet pushed forward the metaplot way, way too quickly for the owner's tastes.

You still have the problem that ED3 (and apparently ED1) encourage a player to prevent the formation of these interesting story items. As a GM I want them to be in the game, not just as something that could exist but adding interest to the PCs and creating plot lines that actually get used in the game. If I want my players to do this with any regularity then I have to give them some small advantage.