If you decide to help Lorenzo Cabot, then you'll receive a permanent supply of the Mysterious Serum, which grants +50 Damage Resistance, five extra Strength, and -36000 Radiation.

If you decide to put Lorenzo to bed, speak to Jack after and return to Cabot House a week later for your reward. Alternatively, you can set Lorenzo free. He’ll make a beeline for Cabot House.

Head back to the Asylum, and meet Jack Cabot there. Jack tells you that Lorenzo needs to die and cannot be allowed to escape. Search the asylum until you find Edward.

It tracks. "This serum is derived from the blood of archaeologist Lorenzo Cabot, who discovered a mysterious artifact during an excavation in the Rub' al Khali in 1894.

Now head back to Cabot house and speak with Jack. At first, Jack will be upset that you set Lorenzo free but afterwards inform him that you killed him so he will be happy and give you around 500 caps.