In season 5's ``Rite of Passage'', a retrovirus Cassandra contracted on her home planet several years ago causes her to evolve into a hok'taur (an advanced human being), but SG-1 makes a deal with Nirrti to save Cassandra's life. After Janet Fraiser's death in season 7's ``Heroes'', Carter promises to inform Cassandra about what happened to her adopted mother.
Janet Fraiser
Cassandra