Sometimes, a normal concussion isn't good enough. When a spaceman exhibits enough brain damage for the dent embedded within the top of their head to collect rainwater, there's a good chance that their brain gets bisected along with it, creating two personalities. With a lack of cooperation, a Split Personality can turn existence hell. With a good amount of cooperation, one can actually turn it into almost a net positive, with tasks being delegated accordingly. Well, if RNG is cooperative in letting each player take the wheel.
Preface
When someone gets severe brain damage (that means brain damage >100), they have a 80% chance of rolling a Severe Trauma. Of the possible traumas within the Severe Trauma pool, there is a 1/11 chance of rolling complete lobe separation, in other words, a Split Personality, manned by a former ghost.
Objectives
As a Split Personality, your first goal is to make sure that your body survives. Other than that, you share the same goals as that of your host. Was your host a Head Revolutionary? Great, now start flashing people. Was your host a Traitor? Great, now try to help achieve their objectives. If your host is a law-abiding member of the crew, stay that way. Any suicidal behavior, A:, is not fun for your original host, who might have invested a good amount of time into achieving things, and B:, is probably going to end up with you getting bwoinked.
Also, make sure that your host doesn't try to cure the "complete lobe separation" brain trauma that is keeping you in existence, as if they do cure it, you'll be completely deleted. It usually should be a severe or greater trauma, so neurine should be okay for your host to drink (check with a health analyzer to make sure that your host's "complete lobe separation" trauma has a "severe", "deep-rooted", or "permanent" prefix in front of it before drinking neurine, though, just to be safe) to cure some of their lesser, more annoying traumas. Stay away from nanites, as the neural reimaging program can delete your host's "complete lobe separation" trauma if it isn't in an abnormally high trauma resilience tier.
Abilities
You and your host will swap places whenever RNG pleases. The period of time in which you have control can vary from a few seconds, to several minutes. The personality which is not in control can telepathically communicate with the personality which is in control. Telepathically means that only the two personalities (and the ghosts) have access to the channel. Besides that, there isn't really much special. The circumstances in which you are placed in, and the actions that you will do, will vary drastically, based on your host. If your host is an antagonist, you do antaggy things. You're naturally going to do different things if your host is the Clown, rather than the Captain.