Introjects are alters which come into the system from an outsid source. An introject is not an original alter, though they often are unique from their source. Introjects come from either media or the real world, bringing in that thing or person they're based on, also known as their 'Source'.

Original alters as I refer to them are alters who are non-introjects, meaning they did not come from a source and formed on their own as a unique person with no resemblance to pre-existing media or people.

Fictives and factives are both introjects, but what's the difference between the two of them? Well, as I mentioned, introjects can come from media or real life. Fictives are introjects which come from fiction, factives are introjects which come from real life.