The preparatory rhetoric invariably depicts a solid communist alliance whose visions of superpower agreement hinge on good behavior by a stubborn U.S. president.

But when Eastern Europe's summit-watchers converge on Geneva, it is likely to be Mikhail Gorbachev, and not Ronald Reagan, who draws their most anxious attention.

Moscow's six Warsaw Pact allies have strongly backed Gorbachev's drive to win concessions from Reagan on the U.S. Strategic Defense Initiative and other arms issues. Yet the most important outcome of the summit meeting for Poland, East Germany, Hungary and other Eastern European nations may be its impact on the developing relationship between Gorbachev and their own communist leaderships.

For Eastern Europe, the Gorbachev era has already meant heightened demands for economic and technological contributions to the Soviet economy, at the expense of internal living standards and western trade. The summit, Eastern European diplomats and foreign policy experts say, could shape the still-lingering question of whether Moscow's new requirements will spread from computers and shoes to military and political affairs.

"The Soviets are already demanding much more effective cooperation on the economic side," said Marian Podowinski, a foreign affairs specialist for the Polish government's official newspaper, Rzeczpospolita. "If nothing good happens in Geneva, there will be pressures for political uniformity as well."

Many Eastern European observers say they see little prospect that the Geneva summit will lead to immediate gains in their own relations with the United States and other western countries, in part because a breakthrough in arms control is considered unlikely.

However, they say a failure by Geneva to improve the atmosphere of East-West relations could place at risk their relative freedom in recent years to pursue national goals and cultivate variations in Soviet-style communism. In East Germany, the stake is closer inter-German relations; in Hungary, it is daring free-market-oriented reforms of the economy; in Poland, it is increased tolerance for debate and dissent in a politically divided society.

Until now, there has been no clear sign that Gorbachev intends to curb the relative heterodoxy among his allies. But neither is it clear to the Eastern Europeans that the Soviets' relative flexibility during the years of detente and frail Kremlin leaders will not now be replaced by a stiff dose of Gorbachev's discipline.

"There's still a lot of visible nervousness and tension about what might be coming from the East," a veteran western diplomat in Warsaw said. Eastern European leaders, he said, "think a failure at the summit could lead to some old-time discipline by the Soviets for everyone and everything attributed to the era of detente."

This risk-conscious outlook means that many communist leaders have focused on minimal summit results. Many say they see no real chance for major progress even on the European arms-control issues that most concern them. However, officials interviewed in several Eastern European capitals were quick to point out that the very staging of the meeting was a welcome result.

"The total importance of such a meeting may be that it happens," said Ivan Broz, an adviser to the Czechoslovak Foreign Ministry. "It will be like a patient with flu who gets his first aspirin. He'll still be ill, but at least the doctors decided to treat him."

Eastern European dissidents, including leaders of the outlawed Solidarity movement in Poland, have a similar view. Most regard a new era of U.S.-Soviet cooperation as a condition for realizing their goals of increased political pluralism. Any superpower dialogue, they say, gives their governments an interest in easing internal repression.

"I'm not that interested in concrete outcomes," said Jiri Dienstbier, a spokesman for the Czechoslovak dissident group Charter 77. "I simply think that any talk is better than nothing."

Outwardly, all of the Soviet Bloc governments have enthusiastically echoed Gorbachev's emphasis on arms-control issues at Geneva. A summit meeting of the Warsaw Pact in Sofia, Bulgaria, last month declared "full support" for Gorbachev's proposal for a 50 percent cut in nuclear arsenals and a ban on space-based weapons. "Now it is the turn of the U.S.A. to follow the positive example of the U.S.S.R.," a joint communique said.

But tensions lie just below the surface of such outward cohesion. Eastern European resistance to an escalation in the arms race was evident in 1983 when popular unrest over the deployment of new Soviet missiles in Czechoslovakia and East Germany surfaced publicly in those countries. Last year, unsuccessful attempts by East German leader Erich Honecker and Bulgarian leader Todor Zhivkov to press ahead with planned visits to West Germany despite Soviet displeasure further underlined the reluctance of Moscow's allies to follow a new hard line.

Even while lining up behind Gorbachev in the pre-summit propaganda blitz, Eastern European leaders have been careful to emphasize their own regional interests. "Other countries have their own place in this process," said a Bulgarian Foreign Ministry official who pointed to his country's call for a nuclear-free zone in the Balkans. "Even Bulgaria can make its own contribution."

Deference to Warsaw Pact views, diplomats say, is at least partly responsible for Gorbachev's move last month to stop conditioning agreements on intermediate-range nuclear missiles on U.S. acceptance of a ban on space-based weapons. The recent Warsaw Pact communique pointedly stressed the possibility of "a separate agreement" on European missiles, and this language was later highlighted in accounts of the Sofia meeting by the official press in Poland and Hungary.

While relieved by the formal detachment of the SDI impasse from their own arms-control interests, officials here remain pessimistic that the summit will lead to quick progress even on European missiles.

"There is a chance to discuss the problems separately," said a Polish Foreign Ministry official who asked not to be named. "But another question is whether it's realistic to expect radical solutions on intermediate arms without solving the problem of strategic and space weapons. I don't think so."

Similarly, most Eastern European officials seem to have few expectations that even a successful summit will lead to significant changes in their own relations with the United States and the West. Even during the 1970s, some diplomats note, U.S.-Soviet detente had only a delayed or muted influence on Washington's relations with such countries as Czechoslovakia and East Germany.

Most Warsaw Pact governments judge improved relations with the West in terms of expanded trade and economic assistance. But the recent increase of Eastern Europe's economic obligations to the Soviet Union and the already-high indebtedness to western creditors of such countries as Poland, Hungary and Romania mean that the possibility of expanding western ties may be limited even if the political climate is favorable, officials say.

Poland may be the nation most interested in rebuilding its relations with the Reagan administration. But while officials here say they hope the summit will set the stage for such an improvement, they are doubtful. "Our hopes are great but our expectations are rather limited," the Foreign Ministry official said.

That leaves the Poles and East Europeans to speculate about the post-summit climate in Moscow.

"What choice do we have? We don't have any choice," the Polish Foreign Ministry official said. "Our course will be determined by whether the summit gives some assurances to the Soviet interests."