They're still kind even though they have all the reasons not to be

I'm looking for characters (doesn't matter if FMC or MMC) who've had a truly sucky life, just really horrible luck. They'd have all reasons to be assholes, grumpy, just plain unfriendly to people – but they're not. They're in fact quite the opposite: very kind, caring, they'd do anything for their LI. They do not have to be super sunshine-y, but I'd appreciate it if the focus was on them having really difficult circumstances, but those did not make them a bad person.

Any genre, any relationship (FxF, MxF, MxM, any with nonbinary characters or poly!)

Thanks!