Peter Quill and Yondu Udonta's relationship is the main father-son relationship in Guardians of the Galaxy Vol. 2.
Peter was born on Terra in 1980 to Meredith Quill and Ego the Living Planet. Being raised by a single mother, while having a fatherless childhood, and seeing other children playing ball with their dad, Peter often walked around with a picture of David Hasselhoff around in his pocket and told other children that he was his father. However, when asked where his dad was, Peter said he was filming or on tour with the band.
His mom made Peter a tape filled with her favorite songs growing up. However, their happy family was short lived when Meredith was diagnosed with brain cancer due to Ego planting a tumor in her head. The last few months Pete had with Meredith were rough. He began fighting with the other boys while meeting raised by his grandfather for a short time.
As a child, Yondu's parents sold him to the Kree Empire, where Yondu spent the first twenty years of his life as a Kree Battle slave. However he was freed by Stakar Ogord, who let him have a place among the Ravagers and saw the team as his family. However, Yondu broke the code after stealing several children from their homeworlds and giving them to their father, Ego the Living Planet. However, after learning Ego was killing his own children, Yondu became the adoptive father of Peter Quill (one of Ego's children) and trained him as a Ravager.
After kidnapping many of Ego's children for the megalomaniac planet, Yondu had enough. Feeling Peter would not be safe on Earth, Yondu abducted Peter from Earth and decided to keep him for Quill's safety. Over time, Yondu began to fall into a fatherly love to Peter and kept his affections for Quill a secret. However, Yondu hid those feelings while trying to stay the leader of the Ravagers.