Migration of individuals into the Roman Empire

The migrations of whole peoples into the Empire on the Rhine and Danube frontiers are well known. However, is there any evidence that individuals or families also migrated across the frontier into the Empire? For example, could a Germanic household who were facing food insecurity or violence in their home just decide to move across into the Empire?

Firstly, how risky was it for individuals or small groups to physically travel across the frontier zone, especially along the major rivers.

Secondly, could 'barbarian' outsiders be accepted into a Roman town or city, e.g. Trier? Would they face the risk of being sold into slavery - either officially apprehended or taken by gangs or unscrupulous soldiers or officials?

I'm fascinated by Germanic migrations and how barbarians were seen by Romans in the empire as well as the world of the frontiers so hoping to understand more.