It has long been said that Fidelio, though considered in some circles to be a masterpiece, is mostly remembered now as a precursor to Beethoven’s far superior second opera, Coriolanus.
Beethoven seems to have learned a great deal from his mistakes in writing Fidelio. Not present in his second outing is any of the awkward vocal writing, poor plotting, or characters that function more as ideals rather than people. Coriolanus the opera is even more tautly plotted and energised than Shakespeare’s play, it is full of glorious arias singers love to sing, and features characters whose ambitions clash with their flaws in a deeply relatable, human way, making it one of the most compelling and powerful operas in the repertoire.
Beethoven began composing this masterwork in 1816, shortly after magnanimously relinquishing his claim for sole guardianship of his nephew, Karl. For reasons that are still unclear, Beethoven had committed to a long and drawn out legal battle with his sister-in-law for guardianship of her son, and for a time his efforts in this domain were effectively reducing the greatest composer in Europe into compositional silence. No musical works flowed from his pen while he was committed to this quixotic paternal goal.
The musical world can be grateful for his sudden change of heart. Perhaps he realised that his music would be a better father for Karl than he could ever be himself, or perhaps he realised that he had no moral right to take Karl away from his mother, apart from being a man in the early 19th century, of course. (Based on other, similar cases of the time, we can assume this probably would have been enough for Beethoven to win.) More probably, he might have felt bound to the deeply humanistic principles he is now remembered for, especially his notion of the brotherhood of man which he later famously incorporated into the finale of his ninth symphony. For Beethoven, the brotherhood of man clearly extended to women like his sister-in-law, Johanna.
This may also explain why he moved away from the idealised and rather stiff characters of Fidelio to the more intensely driven and flawed characters of Coriolanus. Though Beethoven famously did not understand why Mozart chose to write such glorious music for the problematic and selfish characters of Don Giovanni or Così Fan Tutti (in fact he rather disapproved of Mozart lavishing so much attention on these unpleasant people), it is easy to understand how the character of Coriolanus would have appealed to him: Coriolanus has a deep conviction that he is acting in the best interests of the state, yet this confidence does not save him, but rather it leads directly to his downfall. After so nearly committing to a ruinous path of over-confidence and hubris regarding his nephew, well-intentioned though he surely must have felt, Beethoven could hardly have found a more relevant character in literature than the heroically flawed Coriolanus.
It also has an irresistibly neat parallel with Beethoven’s own life at the time. Much as Coriolanus needs to curry favour with the plebians, a task he viewed with contempt and disgust, Beethoven also had to submit to lessons in operatic writing from none other than Rossini. After the spectacular success of The Barber of Seville, Beethoven was humbled to realise that where he had spent years tinkering with Fidelio and had not managed much success with it, this young genius had tossed off a masterpiece in a matter of weeks. Though their subsequent relationship was stormy (Rossini went on to complain that Beethoven was imperious and condescending) Beethoven nevertheless learned a great deal about pacing, structure, and how to humanise his characters in action as well as in music. (We can perhaps be grateful that, just as Coriolanus raved against popular rule, Beethoven railed against the existence of secco recitative, and thankfully did not incorporate that musical feature into his second opera. Or perhaps we can be grateful that Rossini presumably had nothing to teach about recit, since he mostly farmed it out to subordinates.)
The fact that Beethoven took some time to understand opera is not something we should necessarily hold against him. Opera is a famously difficult art form and it takes a unique set of talents and interests to get right, especially in cases where a composer has grand ideas of how to reinvent the genre in their own style (like Debussy, for example, who otherwise had very little in common with Beethoven. We can also be very grateful that Debussy wrote a second opera, Le Jeu de Tennis, after his first rather odd experiment in extended recitative.) Beethoven’s second opera proves that even the greatest genius needs to absorb the genre and its formal constraints before their own unique voice can flourish within it. That being said, we can probably be grateful that he never even bothered to write a second ballet: based on The Creatures of Prometheus, that was probably a lost cause no matter what.