Where they concious the Empire existed? Was more like a legend? Did they know they adored "pagan" gods before being christians? The title "King of Romans" went throught until 1800's I think, but did people remember the time of a more unified Empire than the dismembered pieces that came after it?
Of course they remembered the Romans! Many nobles spoke Latin and were part of the Roman Catholic Church. Your question is regarding the 9th century A.D. so i might as well point out that Charlemagne, ruler or the Franks (France) was crowned "King of the Romans" on Christmas day, 800. The empire was so important that Pope Leo III gave him the title of King Of Rome. Many kings in Europe strive to create an empire like the Romans. In some parts of Europe people could still see aqueducts and Roman ruins. Those men looked upon such structures with amazement at the superior technology the Romans had. Charlemagne especially wanted to recreate the Empire. He even founded schools to teach Latin and wanted his Empire to be much like Rome. This answer would not be complete without mentioning the still thriving empire of eastern rome "the Byzantines". People of Eastern Rome still referred to themselves as "Romans". There are also some Anglo-Saxon poems describing the ruins of a once great empire. Yes, Rome was remembered and to some Rome still existed. Regarding the part about Roman paganism... I'm not sure but i would imagine people overlooked it because the kings of Europe practiced Roman Catholicism.