Old system destroyed, new system not yet established
When you observe human behavior in large groups, you will notice a large amount of inertia. Let's take for example British political system. They have a monarch, with mostly ceremonial duties. They have a parliament, elected with first pass the post voting system, and very powerful Prime Minister. This system has its shortcomings and advantages, but what is most important is that people are used
to it. Average British voter knows what to expected, he may envy countries with proportional representation and president instead of queen, but at the end of the day things were rolling like that for years (with relatively small changes) and he has certain degree of certainty and stability. In the same way he drives on left side of the road, even when the police is not present, he also participates in political system even if he does not like it.
But what happens during revolution ? In certain time and place, people could get so unsatisfied with political system they would want to destroy it. Note negative part - destruction of old system (Ancien Régime) is a primary cause for revolution. What would happen after that is a realm of ideas and speculations. We could take example of American, French and Russian revolution. In each case there was a critical mass of people united by singular idea of removing the old. Anything after that was still untested speculative ideology. And more radical it was, it was more open for subjective interpretation.
As a rule, each successful revolution is followed by brief period of anarchy and "liberty", followed by rule of strong. Note that certain revolutions (like American for example) did not completely dismantle old system (for example common law), therefore this period of chaos was subdued. More radical ones (especially Russian) did away with almost everything, and after that power went to most ruthless, strongest and organized group. Strength would of course depend on lot of factors, charismatic leader could be popular today and hated tomorrow ( Maximilien Robespierre for example), trained soldiers would be more valuable then common citizens, support from abroad would be welcome, firm pre-revolutionary organization could be decisive.
In any case, former revolutionary comrades could find themselves on opposite sides of many political issues. Side which emerges dominant would seek to solidify its position and become new establishment. Others would seek to topple it (including potential counter-revolutionaries). Since these are revolutionary times and old regime is no more, new government would not have privilege of inertia and tradition. Strike while the iron is hot, and everyone with political ambitions would do just that. After all, if old rules and laws were toppled, so could be these new ones.
What then remains is new tyrants worse then old tyrants. In simple terms, new government must use more force then old government to safeguard its position and emerging political system. If they fail to do that, they could face new revolution. But in order to do that they would likely have to spill blood of old comrades, i.e. they would have to repress dissent sometimes even using deadly force. Note at that point population would be mostly weary of instability, and would welcome strong ruler or even dictator. Again, this would depend on how revolutionary was the revolution. In more moderate cases (American) revolution would only eat political carriers of its children, with certain leaders sidelined. In extreme cases we would get GULAG system.