Roger Zelazny's Lord of Light is a classic of this type of story. It's marred by its presentation of gender and sexuality, but still, I think, enjoyable, especially as an example of Zelazny's prose style.

The superhero genre doesn't have tenants, it has tenets. The former are people, the latter are ideas.

It's worth noting that the Doctor graduated from time lord college with a pity degree, and Romana was top of her class. It's never specified just what they studied there, but I would imagine that 'how to control regeneration' would be a likely subject. Thus, I see the Doctor's difficult regenerations as evidence…