Their interaction would be tense at first. Young Kratos, full of energy and unbridled aggression, might see old Kratos as a threat or an obstacle. Old Kratos, on the other hand, would be more reserved and cautious. But as they start to communicate, they would find common ground in their shared past and their connection to their family.
It could be Harry Potter. Since the Harry Potter series is extremely popular, there is a vast amount of fanfiction written about the character Harry Potter. So it's very likely that this 'Harry' refers to him.
Well, it's a bit of a subjective matter. While there are a huge number of fanfictions already, new fans are always emerging and they might want to contribute their own stories. However, from a certain perspective, with so many existing ones, it could be argued that there's enough. There are so many different takes on the characters, relationships, and the magical world that it might be saturating the market so to speak.
Kratos might win. He has fought and defeated many powerful gods in his own world. He is not only physically strong but also very strategic. He could analyze the Hulk's movements and find his weaknesses. The Hulk, while strong, is more of a brute force fighter. Kratos could use his Blades of Chaos to keep the Hulk at a distance and then strike when the opportunity arises. Also, Kratos has faced opponents much larger than him before and has always found a way to win.
One possibility is that it could focus on a mentoring aspect. Old Kratos, with all his wisdom and experience, could guide young Kratos. Maybe he'd show him different combat techniques or how to better control his rage. It could also be a story of self - discovery for young Kratos as he sees his future self and realizes the potential path he could take.
Tyrion Lannister. He is known for his wit and political acumen. Meeting Kratos, a powerful and straightforward warrior, would create an interesting dynamic. Tyrion might try to use Kratos for his own political games or just be fascinated by his stories of battles from another world.
Well, in such a fanfiction, Kratos' appearance as a girl would surely shock many characters in the story. His enemies might not recognize him at first, which could give him an advantage in some battles or situations.