There are major misconceptions about whom and what our ancestors' thralls were and how they were treated. The general belief is that thralls were synonymous with slaves, who suffered under coercion and humiliating conditions.
Thralls, slaves and other laborers arose with agriculture. In the hunter and gather society, slavery did not exist. With agriculture also came war. People became more specific linked to certain areas and lands, and the resources specifically localized. Agriculture and more advanced civilization presuppose such divisions of society, where some are landowners and others work it up, and receive wages for it. In the feudal society, wages were a small piece of land that you could cultivate yourself, and you paid taxes to the owner for that. This is actually also a form of slavery. Seen with today's optics, we are all slaves. Few of us even actually own what we possess. Everyone has to pay taxes. Modern society is very much feudalistic in its current form. In fact, to a much higher degree than our ancestral society was designed.
Many of our ancestors were also thralls. They were ordinary workers. In recent times, we called them “housemates” (Norwegian: “husmenn”). The thralls of the Norse period were not formally free women and men. This meant that they could not vote democratically on the Norse parliaments. The reason for this was that they did not own property (land) directly or indirectly. Likewise, they were not called out for leverage or war when armed conflicts arose. When one was not a property owner, or was required to personally participate in armed conflicts, it was considered that the voting rights would not have the same value. On the contrary, a property owner with military service and an order and obligation to participate in the army, would have the entire risk of an outcome where people with little or no direct risk were included in the voting.
It was considered that society's total interests and progressiveness would be impaired if all citizens were to decide equally. A thralls's risk was far less, in terms of the outcome of a direct democratic election, than a person who owns property and has the duty to defend the outcome of the same result. Therefore, it was probably also a practice that each household had one vote.
In our tradition there was no such thing as voting rights for men, and not women. Both genders had equality, and the household cast their vote. It was also weighted in relation to the importance this household had for society and its members. The husband, wife, son or daughter could represent the household at the Norse parliament, regardless of gender - but the voice seems to have been weighted.
A thrall in the Norse communities was thus homemakers, without voting rights, without property rights. Such a position was not eternal. A thrall could achieve exactly the same benefits as the rest of society. A thrall could legally leave his employer at any time. They could move freely and do as they pleased. They were subjected, in line with other citizens, to the criminal laws. If we were to compare this with anything specific in today's society, they were subject to an oral employment contract.
The thrall Tormod Kark (Skofte Kark) kills Håkon Sigurdsson Ladejarl. The Jarl hid in the pigpen togehter with Kark away from Olav Tryggvasson that had comed to Christianize the tribes by force and to concollidate power. Tryggvasson promised a bounty and a prize for the Jarl´s head, and the thrall Kark could not resist the temptation. Trygvasson executed Kark for this later, because he killed his provider.
In the Norse communities, on a general basis, there was much greater voluntary service by thralls than coercion. Thralls were often personal advisers and allies of the household, and were historically well treated. There is reason to believe, better than similar positions anywhere else in the world.
During the Viking Age in particular, we can read about "army capture" and thralls taken back to Scandinavia. This was especially true of the British Isles. If you look at this historically, and in what situation people without property and at the mercy of others lived on the then Christian North Sea Islands and England, it was probably for many a high degree of voluntary and personal desire to work in Scandinavia. Rights and freedom were far greater here, than defeated European territories elsewhere, subjected to Abrahamic tyranny and the Dark Ages.
The thralls in Scandinavia can in no way be generally compared to what we associate with slaves. If we are to draw a contemporary comparison, the closest we come is to an au pair. Thus, there are unfortunately more "slaves" in Norway today, than ever before.