Expedition: general discussions.

Is this a common occurrence?

We can recall, from classic universes, the D&D multiverse, where there are three distinct races: devils (baatezu) - obsessed with order and rules, manipulative bureaucrats; demons (tanari) - embodiments of mischief and chaos; and daemons (yugoloths) - who don't care about the concepts of order and chaos, often acting as mercenaries for the tanari or baatezu. But here, all three races are inherently evil, and exceptions are found, perhaps, only among half-breeds and those who have been magically influenced (for example, through their true name). It is also worth noting that in the multiverse, demons are created from evil, godless individuals, although I don't remember if this applies to all of them or just leads them all to become yugoloths.
We can also recall the demons in Disciples, whose leader, Bezresen, was actually a very kind fellow, and now he is angry and seeks revenge solely because other angels framed him out of envy, and the Almighty turned out to be a jerk and believed them. Damn, the world of Disciples is in such a mess precisely because of what these envious angels did. The demons now are also not the most pleasant guys, but they don't all serve Bezresen - Uther, for example, tried to overthrow him in the campaign.
Heroes can also serve as a good example: in the cool universe, demons are not demons at all, but aliens, just aliens with a very bad temper and a habit of enslaving the inhabitants. However, in other respects, they more or less fill the niche of their classic counterparts. But in the crappy universe, Ashan, demons suffer more from living conditions and the tyrannical rule of Kha-Beleth, but we are shown that there are also quite pleasant guys among them. It is also noteworthy that Kha-Beleth came to power not least because many demons found meritocracy appealing.
If you need more unusual examples, there is Dragon Age, where demons and spirits are reflections of human emotions. Not entirely a race, but sentient beings. One of their features is that if a person believes that this spirit of wisdom is a demon, then the spirit of wisdom will indeed turn into a demon. At the same time, the line is quite thin, and even not all "bad" spirits, such as sloth or pride, are aggressive. Their aggression is often caused by the fact that they are either a reflection of this emotion, or they were torn from their world and went mad because of the suffering, or they wanted to see what this world is like and tried to enter through a mortal. Sometimes this is caused by a misunderstanding of how human emotions work: the spirit of mercy, Kol, for example, killed suffering people (he did ask for their permission, though). And at the very beginning of Origins, if you play as a mage, we encounter two quite peaceful demons: the first is a demon of sloth and, even if in exchange for a service, is summoned to help us. The other is a demon of pride and spends most of the prologue trying to play on our vanity, but even if the player succumbs to the tricks, he reveals himself in the final of the prologue and gives good advice for the future, instead of turning the situation to his advantage.
There are plenty of examples, in short. Although some of them are minor, for example, in Endless Legend, any empire can assimilate a smaller faction of the Khezanji (they are demons), one of many types of living creatures inhabiting Auriga. Even this is an example of demons portrayed as living beings, and not as the source of all evil.
If you want, it's not difficult to find examples, my friend.