So the plot thickens a little.
Darren is the third son of your tribal chieftain, but that only really sets the stage for your skills. I'll explain more below.
For your backgrounds, there are some required elements I need to see:
1. A strong reason for the two of you to leave your homeland: Maybe you were exiled. Maybe you were framed, or actually guilty of a crime against the tribe, knowingly or not. Maybe the tribe no longer exists? Maybe the designated heir of the tribe was killed? Lots of options there, but I think this has to include your family - otherwise the family would find some place safe for you to be.
2. Something that prevents the two of you returning at this time: There needs to be a reason why you could not seek refuge somewhere else, like Hrothgar's kingdom in Denmark or one of the northern Northman kingdoms. Something must be keeping you from taking that option. Maybe one of you has earned the name kinslayer, one of the highest crimes the Northmen know. Maybe one of you has been declared traitor, and as word spreads you would find no welcome among norse tribes or kingdoms.
3. Some reason for you to strongly dislike Saxons: This game is about Cymric knights, and much of the campaign hinges on the struggle between the Cymru and the Saxons. It would be a lot easier for me if you guys have a strong dislike of Saxons. Maybe your family made arrangements for you to have shelter among the Saxons, but when you arrived they turned on you? Maybe the reason for the exile was actually higher than the two of you, and when the Saxons attacked, the true exile was captured or killed, and you guys managed to survive? Maybe you two and a few followers are the only ones who survived a shipwreck when the Saxons intercepted you? I need this to better incorporate you into the campaign. For example, your hatred of saxons would lead you to seek out their major enemy, the Cymru of Logres, and possibly take service with one of their lords.
Perhaps treason (real or imagined) against your king, King Wald of Ostland, precipitated this event? Maybe Michelle was accused, and her good friend forsook his family and came with her into exile? Maybe Darren was accused, and Michelle followed her friend into exile? Maybe it was someone else, and misfortune struck and the two of you are now on your own (possibly with a small number of followers). Maybe there was a true crime, maybe a false-witness crime? Maybe the tribe was destroyed and you fled - not out of fear, but ti unmask the coward and seek revenge?
I'm not telling you what to write, I'm just suggesting things for inspirational purposes.
In the end, your characters are going to be incredible in Arthurian England, and incredible characters demand incredible backgrounds.
I'm also not too concerned with what the parent rolls and such suggest. Darren's father may well have been a cheiftain, but maybe he died decades ago, and Darren now makes his way as a thrall or common warrior? There is no hereditary right among the northmen. Each man and woman earns his place, so the fact that Darren's father was chief of the tribe sets the tone for some of his stills and his legacy, but it does not determine who Darren is. He could still be a family servant or family friend to Michelle's character. So however you guys want your relationship to be, that's how it is. Among the men of the north, fortunes rise and fall like the tide.
So, let's continue the discussion, but keep in mind the essential elements I'm going to want to see in your shared background.
Darren, I'm going to shift your character development mechanics to a different thread, so we keep this one for the background.