Legacy

"Legacy" is the fourth episode of the third season of Stargate SG-1.

Synopsis
Dr. Daniel Jackson has hallucinations and is soon diagnosed with schizophrenia, possibly due to excessive Stargate travel. It is not, however, schizophrenia but a Goa'uld killing device belonging to the late Ma'chello. Teal'c then ends up receiving the Goa'uld killing device that Daniel Jackson had.

Plot
On the planet PY3-948, SG-1 comes upon a closed chamber. Upon opening it, they discover the dead bodies of the Linvris, a group of nine lesser Goa'uld who fought against the System Lords. However the cause of their death is unclear. Dr. Daniel Jackson looks at a Goa'uld tablet that one is holding and then takes it and a Page turning device for it back to Earth.

Back at Stargate Command, Jackson suddenly starts having hallucinations. At first he sees a member of an SG team as a Linvris and later he sees one of the dead bodies of the Linvris coming out of an activated Stargate in his closet. However Dr. Janet Fraiser can't find anything physically wrong with him, and relieves him of duty, suspecting that he is developing schizophrenia (it is even believed that the cause for this may be the Stargate itself). While playing cards with Colonel Jack O'Neill, Jackson suddenly sees a Goa'uld sneak up and then implant itself in O'Neill. Panicked, Jackson jumps on his friend and tries to stop the symbiote. This final outbreak causes Jackson to be sent into a nearby mental hospital, where he spends the next few days in a white cell, still having hallucinations.

Some time later the rest of SG-1 visits him, shocked at what is happening to their former comrade. During their visit, Jackson sees a Linvris walk into his cell and tries to attack it, but is stopped by Teal'c. However, when he comes in contact with Teal'c, he sees a small, glowing blue thing climb out of him and into the Jaffa. However, when he says this, it is thought to be just another hallucination. He is then stunned, and as he collapses, he says the name "Ma'chello."

Later Teal'c suddenly falls ill. His symbiote is dying, so there is no help for him. Daniel in the meantime begins to recover and decides that the cause of his insanity is a Goa'uld killing weapon designed by Ma'chello, with whom SG-1 came into contact earlier (see "Holiday"). He tries to explain this to Dr. James MacKenzie, the leading psychologist of the hospital, who naturally believes that Jackson is still hallucinating. Jackson then challenges MacKenzie to find out if Teal'c is sick. When MacKenzie discovers that Jackson is right, he releases Jackson back to the SGC.

One of the tablets similar to the one found on PY3-948 is brought to the SGC from Area 51 (where all of Ma'chello's weapons were stored) in hopes of finding a cure. However, when the device is activated, the ten blue things inside it emerge, break out of containment, and infect Major Samantha Carter, Dr. Fraiser and O'Neill. While Dr. Fraiser and O'Neill start to suffer the effect of the weapon very quickly (since they were infected with three of the beings), the weapons inside Carter fall out and die, as she has a protein marker left over from when she was blended with the Tok'ra Jolinar of Malkshur. With Dr. Fraiser's help she uses some of the proteins from her blood to create an antidote, which is able to fool the weapons. The creation is injected into Dr. Fraiser and O'Neill, then into Teal'c, and all of the weapons die.

Notable Quotes
Jackson: Maybe I had some sort of Goa'uld killing invention inside of me; one of Ma'chello's inventions.

O'Neill: And that's what made you...nuts?

Jackson: Well, since I don't have a Goa'uld, a side-effect of this invention must make normal people act like they're...

O'Neill: (whispers)...nuts...

Jackson: Schizophrenic.

O'Neill: (afte being infected by several organisms) I'd like to apologize in advance for anything I may say or do that could be construed as offensive as I slowly.. go.. NUTS!