Perhaps Tony discovers his true identity as Death's son gradually. Along the way, he could face challenges from other supernatural beings who either fear or envy his connection to Death. His relationships with his friends and family would also be severely tested as he tries to keep this secret and navigate his new reality.
There are so many fanfictions out there, and finding the 'tony is death son fanfiction' might take some time. You could also join some relevant fan communities. For example, on Reddit, there are often groups dedicated to specific fandoms. Post a request there asking if anyone knows of such fanfiction. People in those communities are usually very helpful and might be able to point you in the right direction.
Tony may develop a darker side. The allure of the Infinity Stones' power could corrupt him. He might start to make decisions that are not in the best interest of the world but rather for his own gain or to satisfy his newfound thirst for power. This would create a lot of conflict, both within himself and with his friends, and add a whole new dimension to the fanfiction.
Well, it could start with Percy being in awe of his famous uncle. Maybe Tony initially sees Percy as just another young relative but as time goes on, he realizes Percy has a unique set of skills or a great mind. They might start working on projects together in Tony's high - tech lab, gradually building a closer bond like a mentor - mentee relationship that evolves into a more equal partnership over time.
Tony might be initially skeptical. He's been through a lot and has trust issues sometimes. So, he might not immediately accept Rhodey's apology. For example, he could give Rhodey a cold look and say something like 'We'll see if you really mean it.'