Some our users might be interested in this article from the most recent issue of Saga Book: Viking Society for Northern Research.
Stephen Lewis, "Rodulf and Ubba: In Search of a Frisian–Danish Viking"
http://www.vsnrweb-publications.org.uk/Saga-Book%20XL.pdf
"Rodolf was a prominent Frisian-based Danish Viking leader in the third quarter of the ninth century. When he was killed in 873 while trying to wrest lands for himself in northern Frisia it was reported by Archbishop Hincmar in the so-called Annals of St Bertin that he ‘had inflicted many evils on Charles’ realm’. The East Frankish Annals of Xanten reported that he had ‘wasted’ many regions over the sea (transmarinas regiones plurimas . . . vastavit), as well as everywhere in the kingdom of the Franks, in ‘Gaul’ and in Frisia. Rodulf was the epitome of a much-travelled Viking.
"This article attempts to reconstruct some of Rodulf’s life and deeds. It will be suggested that his activities were not limited to Frisia and Francia but probably also encompassed Ireland, where a Scandinavian leader called Rodlaibh (Rodulf) was active in the early 860s, and possibly even earlier. More tentatively, it will be proposed that Rodulf could well be the same man as one of the early leaders of the Danish Great Army in England, called Ubba ‘dux of the Frisians’."
The two men discussed in this article are on Geni as Rodulf Haraldsson and Ubbe Ragnarssen. Ubba, of course, is one of the men we were have heated discussions about in relation to Ragnar 'Lodbrok' Sigurdsson King of Denmark and Norway. We've mentioned Rodulf from time to time as a possible relative of Grand Duke of Novgorod Rurik.
I want to emphasize that the theories in this article are just theories (for now). We might use some of the documented information in the article to build out our Geni profiles, but we should not expect to change existing relationships on Geni. It's just an interesting intellectual exercise -- what if ...?