To be fair: a lot of times gamemasters (GMs) shouldn’t give out strings-attached rewards to player-characters (PCs). Particularly if the PCs in question spent character or experience points (XP) on those rewards; one of the basic unwritten rules of roleplaying games (RPGs) is “If I paid for it, it’s my chew toy, not the GM’s.” GMs who forget that tend to have high turnover in their games. …Still, sometimes it’s more interesting for everybody involved if the gifts that the players get from the GM come with a few amusing extras attached. Keeps people on their toes.
So, some possibilities:
Fame and awards. So a player or group has just did something that, in real life, would have resulted in a major award for valor: something, say, at the American Medal of Honor level. Well… they should get that major award. And the GM should make it clear that everybody in the kingdom or star nation or whatever knows that the player/group got the major award, too. Why? Because now the GM has a perfect excuse for deciding that the party is going to be under more public scrutiny. Think about it: a regular soldier or even officer can get away with being in a bar fight. Sure, if they get caught then they’re in trouble, but if it’s kept quiet they might very well not get caught. But when a Medal of Honor recipient gets caught in any kind of problematic situation it’s news. And people who have been given that kind of award are generally expected to live up to its standards.
More general fame—or notoriety—works under the same basic principles, except that the consequences are shallower, yet broader. Regular celebrities aren’t held to the same high standards as war heroes, but many more people will feel entitled to criticize celebrities when they don’t live up to the hype. And there are so many more opportunities for a celebrity to be caught out not living up to the hype. Indeed, there’s an entire branch of our media that’s dedicated to this sort of thing: any game world with a recognized entertainment industry will probably have something similar.
Royal “favor.” It is said that Elizabeth I of England had a viciously elegant way of foiling serious domestic conspiracies against her rule; she would simply visit the conspirators. After two weeks of hosting the Queen in a manner befitting a Queen, the ‘lucky’ nobles would typically not have the money to fund further intrigues against the Crown. This trick could be repeated nigh-infinitely, and is certainly one way that a local monarch can complicate the party’s life, whether they’re landowners or not. There are advantages to being in a monarch’s inner circle, naturally. Rather powerful ones. But it can also seriously circumscribe a person’s behavior.
One particularly entertaining thing to pull on PCs without land is to give them land. Only, it’s not quite productive yet, thanks to the plague / war / bandit raid / collapse of the western border a few years back / zombie outbreak. Making the party fix up the place serves two purposes: it gets a broken portion of the realm put back to normal and it puts a bunch of useful, yet potentially dangerous, people on the shelf for a few years. Or decades.
Better gear or resources. Give a man a fish, and you feed him for a day. Give a man a +4 Rod of Aquatic Animal Control, and you can legitimately assign him every vaguely piscine-related problem of the Realm’s for the rest of your, or his, life. The corollary to that is that the PC will undoubtedly insist that he receive the resources needed to maintain, repair, and/or replace the gear so generously given to him, but from a pragmatic head of state’s point of view that’s perfectly reasonable. Especially since said head of state can then insist that the PC consistently perform at a higher level of efficiency and effectiveness. …Fairly! That’s the nice part about this one: it’s perfectly reasonable to give the people with the good track records and the best gear the hardest jobs.
One last note: giving a ‘reward’ to a party of adventurers by making them essentially protect a high-ranking, yet bratty, incompetent, or fragile non-player character (NPC) is a bit of a cliche in many campaigns. I’d avoid it, if only because it’s been over-used. If you want to do it anyway, a more subtle, yet ultimately profitable, tactic would be to make the NPC actually able to keep up with the rest of the party. If you’ll do it correctly, the party will forget that they’re supposed to be keeping him out of trouble, and instead let him come along to start some. You let that happen for a while — and then put the NPC in danger. That should keep them more emotionally invested in the situation, I suspect.