One interesting story could be an Imperium of Man crossover with Warhammer Fantasy. In this crossover, the Imperium's advanced technology clashes with the magic and medieval setting of Warhammer Fantasy. It could explore how the Imperium's Space Marines would fare against the Chaos forces in that realm.
Character development is key. When bringing together characters from the Imperium of Man and another universe, show how they interact and change. For instance, if an Imperial Guard meets a Jedi from Star Wars. The Guard might be initially skeptical of the Jedi's use of the Force, but as they work together, they come to respect each other. Also, don't be afraid to deviate from the established canon a bit to make the story more interesting.
It's mainly about the Imperium of Man in a dark and complex setting. It delves into the politics, wars, and various factions within the Imperium. There are power struggles, battles against alien threats, and the exploration of the dark secrets that lurk within this vast galactic empire.
As I don't know the specific 'imperium real story', I can't say for sure what the main characters are. They could be emperors, generals, or ordinary people who play a crucial role in the development of the imperium.
Yes, it's definitely worth it. The story is full of action and intrigue, set in the rich and complex Warhammer 40K universe. The audiobook version brings the characters and their struggles to life in a vivid way.