“‘Who exactly are you?’ said Cu Chulainn.
‘I am Lug Mac Ethlenn, your father in the other world.'” (pg. 104)
This quote gives another perspective on Cu Chulainn. At the beginning of the story, Cu Chulainn is presented as extremely powerful and strong but a human. However, this passage shows that Cu Chulainn has an immortal father and so he is part immortal. The fact that his father from the other world comes to help him is important because it demonstrates how Cu Chulainn is respected by the gods, in particular, the god of light, because he is very successful and honorable. The gods want to protect him. His father from the other world aids him by healing his wounds and protecting him while he sleeps, so Cu Chulainn can continue serving as a hero.
I agree that this quote gives us good perspective on Cu Chulainn. To me it shows that he is quite similar to mythical heroes of other religions as well. The most apparent would be Heracles, as the two have very similar backstories and heroic journeys. Like Heracles Cu Chulainn is a son of a god who inherits great powers from his father and uses them mostly for battle. Another good comparison would be Karna from the Mahābhārata. Karna is also the son of a god of light, or more aptly the god of the sun. Also like Cu Chulainn Karna must fight his brother, however in the case of Karna he actually looses and is killed by his brother Arjuna.