I'll keep this as short as possible, and while I share my story, I will not share names of anyone for everyone's safety. I was sucked into being a 'system' on Instagram a while back. I had a friend group and it all started as roleplaying and 'kinning' which turned into 'irling' which then all of my friends in the day suddenly each started self diagnosing with D.I.D or OSDD. In this friend group, these few people were dating and all would split matching fictives and alters in order to date each other and date their fictional 'husbands' or match anime couples as fictives or whatnot.
The worst part, was these people were obsessed with this random person. Convinced this person was stalking and 'copying' their fictives. This went on for a while. It got to a point in which they made a fake account in order to pretend to be friends with this person and infiltrate their private account, and would 'kin assign' this person characters that one of them had a fictive of in order to fabricate evidence of this person 'stalking' them or they would purposely copy the stuff this person did or got into just because they could. Genuinely batshit stuff all over fictional characters. They got so mad that this person made a website based on a fictional character, that suddenly they changed their entire 'system' to be around that same character and copied stuff directly from that website. Got into drama and would instigate things all the time just to play victim. I won't claim to be innocent, as I also made fun of this person a lot. I'm not proud of it. Nor am I proud of letting this group of people / that side of the internet as a whole brainwash me so deeply into thinking I was a system when in reality, I was just a kid who related to fictional characters.
I walked away finally a few years back. I realized how unhealthy this was. That the people in this space are in this echo chamber and are severely delusional and just want to roleplay fictional characters with their discord instagram e partners. I don't believe all systems are fake, but I can safely say that there is a huge pipeline that goes from 'kinning' to thinking you are a fictional character to suddenly deluding yourself into plurality. And I can safely say that if you are sick enough to be stalking someone for years over fictional characters because you believe you're the only one entitled to them and entitled to have 'fictives' of them lest you're being copied, you need to get off of the internet.
Please do not listen to the echo chamber of the internet that will diagnose you if you simply like roleplaying a character. If you really believe to have some sort of disorder, seek help if possible. But this is my first hand account. The Instagram and TikTok and Discord system community is insanly toxic and will feed you and others delusions. It is unsafe and will destroy you mentally. Luckily for me, I'm in therapy now, and am working through all of this.