In the 9th century, Viking raiders brought enslaved Black people from North Africa to Ireland. Here is the Irish annal entry (translated J. N. Radner):

Then they brought a great host of them captive with them to Ireland, i.e. those are the black men [literally 'blue men']. For Mauri is the same as nigri; 'Mauritania' is the same as nigritudo. Hardly one in three of the Norwegians escaped, between those who were slain, and those who drowned in the Gaditanian Straits. Now those black men remained in Ireland for a long time. Mauritania is located across from the Balearic Islands.

We don't have sources from the Vikings themselves about this event, although Viking raids in North Africa are corroborated by Arabic sources. Thinking about the Irish annalists though, they seem interested in commenting on the geographic origins of these people and linking it to their skin colour. The Irish word used to describe their skin was actually gorm (dark, reflective blue), not dub (black), but they are giving a Latin explanation for the black skin of the people in question and trying to link it to the etymology of where they came from. Slavery was very common in Ireland, so the enslaved Black men probably just intermarried with the local enslaved population.

That's about as close as we can get to a historical account of interactions between Vikings and Black people. It doesn't tell us anything about what the Vikings themselves thought of meeting a Black person. However, the Vikings spent time in cosmopolitan places like Constantinople where it would have been very normal to meet Black, Brown and Asian people. Black people have lived in Europe in small numbers for thousands of years, which I've written about here.