Forkert (Germania) was weak as a child, making him an easy target for bullying. However, Romulus (Ancient Rome) didn't just sit by and watch his friend be bullied. He stood up for Forkert, eventually, everyone left the Germanic boy alone.

Though Forkert felt guilty Romulus had to rescue him.

Which is why when they were older, Forkert became Romulus' 'body guard', to protect him/return the favor.