"I don't get mad," Aris Mardirossian says. "I get competitive." So The Southland Corp. can attest.

Back in 1984 Southland considered setting up one of its 7-Eleven convenience stores in a building Mardirossian owned in Gaithersburg, Md. Terms were negotiated, and the Armenian immigrant signed the papers and shook hands. But the deal fell through. Mardirossian's version is that the higher-ups at Southland's Dallas headquarters decided they wanted more favorable terms. A Southland spokesperson says Mardirossian misunderstood the company's procedures.

In any event, Mardirossian -- who had already evicted the previous tenants -- was upset. But he had an idea. "I said, 'If that site was good for them, it's gotta be good for me.' I decided I was going into the convenience-store business, and I'd do it better than 7-Eleven." A month later the first 6-Twelve Convenient Mart opened at that location. "I was making very easy money."

Soon Mardirossian opened a second 6-Twelve, this one across the street from a 7-Eleven. "That store took off like a bonfire." After he opened his third store, across from yet another 7-Eleven, he says, Southland sued for trademark infringement. "The spirit of competition totally poured out of me." Retaining the Chicago law firm that had helped MCI take on AT&T, Mardirossian fought back on antitrust grounds -- and won.

Today 14 6-Twelves do business in Maryland, Virginia, the District of Columbia, and Connecticut, with 15 more under construction and plans for future expansion. All but 3 are franchise operations. Mardirossian looks for locations, he says, that are "as close as possible to a 7-Eleven or whatever the local chain is." Typically, the 6-Twelve is larger than its competitor, with an on-premise bakery and deli, and without the magazine racks and video games that draw teenagers.

The formula has worked well for Mardirossian, a 38-year-old engineer and restaurateur. He has recently built a stone mansion in the rolling Maryland horse country northwest of Washington. On the gate is a bronze plaque that reads: "Thank Heaven for 7-Eleven."

-- Jill Andresky Fraser