He underwent a special training program under the supervision of SG-1, during which he failed to impress Colonel Jack O'Neill much. In one training scenario, he shot Major Samantha Carter with an Intar, mistakenly believing her to be a Goa'uld. (He was subsequently shot by Dr. Daniel Jackson, the actual Goa'uld in the scenario.)
Despite this incident, Carter asserted that Grogan would make a fine addition to an SG team. O'Neill, however, thought he would make an excellent target, noting his propensity for getting shot. (Grogan was shot at least three more times during the course of the training.) For his part, Grogan concluded that O'Neill simply didn't like anyone, and expressed irritation at fellow trainee Lt. Jennifer Hailey's repeated mention of her exploits with SG-1. Nonetheless, Grogan distinguished himself sufficiently in the final training scenario to earn a post on an SG team. (SG1: "Proving Ground")
One of Grogan's first assignments was a long-term mission to the planet Latona, as a member of SG-9; his team's mission was to negotiate access to an advanced weapon known as the Sentinel. During this time, Grogan became well acquainted with the Latonan city and their leader, Marul. After several months there, the planet came under attack by Jaffa loyal to the Goa'uld Svarog, who killed every member of SG-9, leaving Grogan as the only survivor of the team. After he made contact with Stargate Command, Grogan came under fire and spent most of a day trying to avoid a Jaffa patrol. Ultimately, he decided to make a stand, but passed out on the roadside instead; the Jaffa apparently missed him, and he was recovered by SG-1.
Rather than send him back to the Stargate, Colonel Jack O'Neill had Grogan find them a way into the Latonan city to see Marul. After a lengthy meeting in which Grogan and O'Neill attempted to convince Marul to evacuate his people, the two were stunned with Zat'nik'tel fire and captured by the occupying Jaffa. They were then taken to the site of the Sentinel, and were saved when the device's activation caused all the Jaffa to disappear. (SG1: "The Sentinel")