Bad Endings -
Derrick's Questline - Fail to defeat the third boss in the subway to get an ending. Defeat the fourth boss or be defeated and get a different ending.
Machine God Questline - You will be asked to aid in figuring out the mystery behind strange red portals, each portal offers a ending if you fail to escape from there.
??? Portal - After aiding the Machine God with his five portals, a sixth will appear, but only if you had been working as a officer with the K-9 police department.
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Submission Endings -
Brutes - Same with the prison, but happens in the UnderBelly only.
Drugs - Take too many drugs while in the UnderBelly in Roscoe's hideout (find the hideout after aiding Roscoe in his questline.)
Junkyard- Be captured and fail to escape.
Nitric - Help the Torni Construction Company (aid Kira until you meet Torni, the owner) until he tells you about the sewer. Go into the sewer and survey around until you fight a boss. Speak with the boss and then aid him by repairing the sewer. Repair the sewer to 0 stamina 3 times and then speak with the boss afterwards to gain Nitric. Train with Nitric, or lose your stamina in the sewer and be taken over by him, to get this ending. Changes if you have bonded with York.
Prison - If you get into prison (mostly by passing out with 0 or less stamina and have less than 5000 credits) you will go to prison and have a chance of having too many odd dreams at night. Too many of them will lead to an ending.
Subway - Fall to exhaustion too many times within the subway.
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Character Endings -
Alejandro (Barista) - Go and get a coffee from the shop in the Downtown area 5 times until you can meet him. Meet him and then help around the family business to access his questline. Complete his questline and then flirt/play with him until you get his ending. His ending has an alternative ending if you follow him at night five plus times until you see a scene.
Arnold (Gym Lion) - Help him with his questline and then exercise with him until his ending is accessible.
Canine Roommate (Ne Athens' Apartment) - Pet him until you get asked to do more for him. Do more until you see a scene, and then sleep with him/do what he wants until you get his ending.
Coach Whyte (Stadium)- Go to the stadium via the subway and then join the team. You get one ending if you are a team player, you get his true ending if you become the water boy (become the waterboy if no stat is 40+). Follow through with his questline until he asks you to meet him at night.
David (College Bully) - His endings will be determined by his Submission/Domination stat which can be toggled depending on you relationship with him, but you will need to help him through his questline first. If you keep a handle over him you can get an ending after 25+ times dominating him. If you don't keep a handle over him, you can get a submissive ending after 25+ times letting him have his way. You can get an advance submission ending if you are intelligent enough and help him get into the military.
Derrick - Meet him after winning the PIT coliseum fights and then help him and his wolves with a problem in the subway. 1st boss defeated in Subway will gain access to his questline. 2nd boss will access the werewolves interactions.
Roger - (Casino Owner) Help Roscoe until you meet him, and then work with him at his casino (following aiding him in his questline) until you get his ending.
Lahou - (Tiger martial artist) - Meet him after winning the PIT coliseum fights and then train and then challenge him for the title of master.
Sergeant Anderson - Join the K-9police force (must choose Punk Class, go to temp agency and go to prison and then get out) and then help through his questline and then flirt/play with him until his ending appears. He has a second ending if you play around with his pack.
Sergeant Cooper - Join the regular police force (must choose Normie Class) and then help through his questline and then flirt/play with him until his ending appears.
York - Defeat the PIT A-Rank and then find some missing persons in the Back Alley notice list before meeting him in Mutate Fun House. Help him through his questline and then flirt/play with him. He has a second ending if you bond with Nitric before you get his ending.
Zodagh - Defeat the PIT D-Rank until you come across him. Defeat him and follow him into the Back Alley until you meet him again. Fight him again and the aid him in repairing his lair until you get through his questline, then flirt/play with him until you get his ending.
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Military Ending -
Qamar (Krogan Commander) - In order to get his ending you must fight until you get a special scene on the other planets you visit. Help out the character you meet during these times, meaning help once and then see them again after fighting again, and then fight until you see them a third time. You will get a special scene with them where you will find a relic. After finding this relic go and find the spaceship you see in a vision and you will get a special scene with at the end. For every one of these special scenes you find Qamar will like you more and more until, after the fifth time, you get his ending.
Hish (Predator Aid) - Find a relic, go to a ship and then return back. DO NOT AID THE CREATURE YOU FIND WHEN/IF YOU SEE IT OR HE WILL COMPLETELY IGNORE YOU. Basically, do less than you would for Qamar and he'll be interested in you.
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Other Endings -
Museum - There are five different 'timelines' that can be found based on your character class, each one has three different endings that you can find if you interact against Meelak's advice.
Teacher at College - Be a model student until see the option to become a teacher.
Pit - Get defeated by certain creatures
Arena - Rank S Boss Fight