I believe there are several. As there are several ways stalking can be done and the extent that stalking can be taken too.
You have online stalkers who are just being your average nosey folk. Just wanting to see what you’re doing. Then you have your dangerous stalkers who most likely suffer from some sort of psychopathy.
I’ve noticed harsher mercury- Pluto aspects tend to showcase these traits. The opposition, square, and at times conjunction. If Venus is thrown in the mix it can make matters complicated.
The 6th house synastry can indicate stalking believe it or not. Especially if Pluto is in you or your partners 6th house. It creates an obsession to know the who, what, when, and where’s of the individual. If it makes aspects on the 8th, or 12th things can become even trickier. But 6th house is daily routine so Mercury Pluto aspects there in general are indicative of this. Pluto ascendant aspects as well.
If Neptune is thrown in the mix then you can have paranoia or fear of being stalked. Or thinking you’re being stalked. So many things to analyze.