No, it's not. 'A Bear for Miguel' is likely a fictional storybook, as many children's storybooks are based on imagination and creativity rather than real events.
The main characters in 'ilustrado' are likely to include individuals who represent different aspects of the society it portrays. There might be a young, curious protagonist who is on a quest of some sort, perhaps to discover his roots or understand a mystery related to his family or the society. There could also be older, more established characters who act as foils to the protagonist, providing different perspectives on the events and values in the story.
Power is a major theme. Two Lucifers would bring a lot of power into one story, and it can be about who has more power or how they use their power together.
In the world of 'lucifer meets lucifer fanfiction', a common plot could involve a clash of egos. When two such powerful and complex characters meet, there's bound to be conflict. Some stories may also explore a romantic or at least a deeply emotional connection between them, as they are essentially the same being in different forms, and this connection can be both fascinating and disturbing at the same time.