Hello! I have begun to suspect I'm a system. Mostly, because of that feeling of just being a different person, or temporarily/partially a fictional character. I suspect it's more of a "median" thing, if I'm not misusing the term, although occasionally there are minor instances where I might be experiencing amnesia, like there might be someone regularly giving homeless people much bigger bills than I originally intend to give out, and I'm way too fastidious to be making this mistake this often. However, I admit I am quite frightened. I feel like I'm trapping someone else in my shitty life and ill body, with even less autonomy I already lack. I also can't help but be at a loss of what kind of things I would talk to these people about, and have trouble thinking of what kind of value I would bring to them as a companion. Some of the people I think might be here, are pretty impressive fascinating individuals. I am someone who has nothing going on. I'm scared of puppeting them or abusing them, already exerting terrible control without even knowing it, if there really is a whole person rattling around in there. I am also admittedly scared of losing control. The idea of someone possessing my body and ruining my life is extremely scary to me. Of there being someone who I can't leave or escape at all. I'm an extremely private person, who values my independence, and is slow to trust. And lastly, I guess I'm scared they'll hate me. I have a long history of being disliked and mistreated, and I don't know if I could bear it if it came from someone apart of my very own mind. I don't know. Thanks for listening. Any advice, I guess?
It's okay to be scared! Many systems are when they first approach the idea that they may be one themselves. Try to take the idea slowly, and as it comes. We suggest managing each new situation involving your system as it arises, and not stressing too much about the details for now.
Generally, from what we've seen from tulpas (an example of a headmate with less autonomy in the beginning) they're usually just happy to exist with their host no matter the circumstances, and resentment usually only forms if the host is abusive, or there was trauma beforehand that led to that headmate. They don't usually feel trapped or upset at existing, assuming their host treats them well. Regardless of whether your headmates are tulpas or not, this might hold true for you too.
You could talk to them about anything, really. As you're going about your day you might think to yourself about various things, and if they overhear they might be able to add their input. Conversations don't always have to be about big things, they can be about the ordinary as well. If they're impressive people, then it might be nice for them to talk to someone who isn't impressive in the same ways they are - so you wouldn't be boring to them, you might actually be interesting in your own right. And even if you did have nothing going on, some interesting people might be tired of talking to others like them all the time, and find this to be charming. (Think of it how some learned people are delighted to talk to someone who knows nothing of their profession, to tell them about it for the first time.)
The best way to avoid accidentally puppeting them or abusing them is to listen to them when they say they said (or didn't say) something, and respect their consent (or lack of it) in situations that involve it. Accidental puppetting can happen, but it's often a result of the mind being finicky and/or intrusive thoughts, and talking to the headmate usually rectifies the issue. AFAIK it doesn't hurt a headmate to be accidentally puppetted, and most are forgiving when it does occur.
While losing control can be scary, it's not usually something that happens without a reason. Many (but not all) endogenic headmates need some sort of permission to control a body, and even in the case of traumagenic systems usually they won't take over and ruin your life just like that. Trauma can be a factor with a headmate that does take control and refuses to give it up, or otherwise does not appear to compromise with the other sharing their body, but even that can be mitigated by just being nice to them, respecting them, and if possible seeking out therapy for the more traumatized headmates (if they exist). When someone does lose control suddenly, it's more likely to be a result of trauma or triggers, and the headmate taking action to do what they feel is best for the system.
To a certain degree you'll still have privacy inside your own mind, depending on how your system functions. You mentioned minor instances of amnesia, and that in itself might provide you some privacy, but for some systems there are ways to obtain at least partial privacy - we've heard of systems that can choose how much they want to know about the other headmates or prevent unwanted information sharing, and others who strengthened certain mental barriers over time for their own comfort. Headmates may not always be awake and active (many "sleep") and during these times you may find your mind silent, or have the place to yourself temporarily. It is possible to get some level of privacy as a system, even if it may never be the same as a singlet might have.
If there's no trauma or abuse behind them, it's unlikely they'll hate you, especially for no reason. Even in traumagenic systems, there are often many system members who do get along, or can at least work together for each other's benefit. And if they do happen to hate you, it is often possible to rectify any issues by discussing them (why do they feel this way? Is there anything that can be done? What are their needs?), and figuring out solutions together.
Discovering you're a system can be a huge change, and it's alright to be scared. There are ways to mitigate any potential issues that come up, and enjoy being together. Sorry this took a while to answer, but hopefully this helps ease the fears!