If we ever see Marty in the present day, you think maybe has a turned over a new leaf and is a better person, or is still the same jerk as he was in the past?
Marty a character we know through flashback, he is similar to Baron in Sym Bionic Titan, I remember when I watched that show what kind of person is present day Baron, still the same jerk as before?
Signs point to Marty still not being a good person, as we know he has never been a part of Sour Cream's life not as any intention to? Though he might not even know he has a son, but that detail is still unclear.
A sceneo I thought of, maybe Marty he changed his life around, become a better person, he got married, had kids, and is a great dad to those kids. How would Sour Cream feel if he found that out. He probably has no emotional hattachment to Marty, and has Yellow Tail as his father figure, but still you have to feel a little rejected.