When Queen Aleena left Manic on a doorstep as a baby, his basket was stolen by one of Ferrell's friends. Ferrell was surprised to find the baby inside, but soon took to him and rather than throwing him away, raised him.
Along with many other young street urchins, Ferrel taught Manic all he knew about the art of stealing, but considered Manic his best and favorite student. Seeing as Manic is essentially a good person despite his kleptomania, it is clear that Ferrel also taught him to sympathise with the poverty-stricken, think of all people as equals (even if only as equal targets) and to consider violence as a last resort - clear from Manic's laid-back attitude.
While they are clearly fond of each other, seeing as Manic often regrets not having home or a family growing up, it seems he never truly thought of Ferrel as his father.