Disclaimer: completing this content will result in sweeping changes to Primrose's personality and affect his ending options as well. While the spirit of the character is still there, it is a major shift in demeanor.
Also, this plot line will take weeks in-game to complete. It is best to tackle it in chunks.
After rescuing Primrose from his reprogramming, you will receive footage from AIKO that reveals the truth behind Primrose's origins. You can choose to send the footage to Prim or keep it to yourself. This is the point of no return.
After work, you will receive a message from AIKO alerting you to a situation in Primrose's lab. Hustle down to R&D and discover Prim locking himself in his lab and in VR.
Follow him in and confront a specter from the past. He will ask you to talk to Dr. Synthea about his situation. He will be unavailable to visit until after you talk to her.
Talk to Dr. Synthea about the situation. She will connect with AIKO and start the healing process. If you visit Primrose's lab, you will be denied entry while he is 'away on vacation.'
While preparing to leave work on a night where you do not have other plans and have completed the above content, you will receive a delayed message from Primrose asking you to meet him in his lab. You will go down to his lab and discover the scientist in a predicament.
Review the footage with AIKO and attempt to free Primrose. While unsuccessful, you will think up at least one (dangerous) course of action. You will be guided to the asylum layer to ask Nursula for her assistance.
Return to the lab with Nursula in tow and watch her practice her bedside manner. After the scene resolves, you will need to talk to Dr. Synthea during regular therapy to continue the thread. If she has not been rescued yet, you can find the details on how to proceed here.
Talk to Dr. Synthea during Friday therapy to ask for her assistance with Primrose. She will agree to help you with mending him.
During Wednesday or Sunday VR therapy, you will be presented with a new option to assist Dr. Synthea with her work with Primrose. You can agree to help or choose to do a regular simulation. If you have Cruel Therapist enabled, you will be forced to help her with Primrose.
Play through the therapy session. You will be presented with an opportunity to be Primrose's snuggle buddy for the simulation. If you have a Domination of 15 or higher, you can choose to cuddle him instead. Either way, the scene will play the same from there.
You will receive a phone call from Dr. Synthea asking for your continued help with Primrose. Accept your new task (and a small pittance).
During the next VR session you opt into (or are forced into), you will play the part of Primrose in an average day in his life. Upon proceeding, several cutscenes will play in sequence. It is recommended that you set aside sufficient time to view these scenes in their entirety.
Within a week of the previous event, you will receive a phone call from Nursula Sprocket letting you know that you can visit Primrose in the asylum now.
Visit the asylum after work and go through the first VR therapy session.
Talk to AIKO in VR at home. You will now have access to the VR therapy program from home. You can visit Primrose in person at the asylum still but progression will be done through home VR.
Complete the Lorelei VR therapy sessions. You can complete them all in one sitting but you won't see visible progress until you return to work.
You need to have completed the Twig Destruction quest to unlock the next part of this quest.
After Twig is disposed of in the matter you best see fit, you will receive a phone call from Nursula letting you know that Lane has returned to his laboratory.
Visit Lane in his laboratory to get to better know the 'real' him. You, Lane, and AIKO will begin to brainstorm his escape. You will need to find a person willing to take him in after the escape.
Talk with the various candidates to whittle the list down to only the viable candidates.
Meet up with Lane again. You will now have a list of candidates along with requirements to make each of them work. The requirements are:
You - Romance locked. Since the romance option for Lane isn't in the game yet, you might want to hold.
Antlers - You need to be dating Antlers to take this option, as well as having talked to her about taking Lane in.
Dr. Synthea & Candy - You will need to have completed the Primrose AI therapy program and have talked to both of them.
Dr. Toru & AIKO - You will need to have completed the Unit 1104 AI therapy program.
Krystal - You will need to have completed the Nyx AI therapy program and have talked to her about taking Lane in.
Herman - You will need to have completed both the Nyx and Unit 1104 AI therapy program as well as talking to him about taking Lane in.
Governess Watergate - You will need to have completed both the Primrose and Nyx AI therapy program.
Mistress Omino - You will need to have completed both the Unit 1104 and Primrose AI therapy program.
Church of the Goddess - You will need to have talked to a church representative about taking Lane in.
Nursula Sprocket - You will need to have completed all three AI therapy programs. This will begin the Nursula Finale quest (coming in 1.0.2.X)
Once your decision is made, you can execute the escape sequence. If you selected Watergate or Omino, this will simply be one last cutscene. If you picked one of the others (besides Nursula), you will have to complete the escape. When you reach the guard, you must choose how you will convince him to let you deliver the box. All options work, though choosing to leave Lane unattended will have consequences later.
And now you're done! Lane's epilogue will show up with a card depending on what you did (or didn't) do.