While he is an avid hedonist who is fond of drink and leisure, he is also a devout Centauri patriot and would gladly give his life without hesitation to protect the Republic.
He resents the Narn for their eventual success in establishing themselves as a viable independent power and for what he feels is their part in the increasingly unimportant and humiliating political positions he has held in the latter years of his life, most of which were diplomatic titles with little significance in the royal court.
Londo's greatest desire is to see the restoration of the Centauri Republic to the glory and influence it held in older times, and it is this desperate longing that proves the undoing of himself and his people.
Londo is very appreciative of his friends and reluctantly tolerant of insincerity; he often chooses the friendship of people with temperaments similar to his own but with personalities suited towards brutal honesty (Michael Garibaldi) or sincere naivety (Lennier, Vir Cotto).
Of the three wives he possesses, the only one he does not divorce is his abrasive wife Timov (who absolutely despises him and shows him not the slightest shred of respect) because her scathing honesty is preferable to the feigned friendliness and scheming of the other two.
His greatest love, other than his people, is the romantic company of Lady Adira, a former slave and dancer whose benign and sincere nature pierced all the practised cynicism he has built over the course of his life.
Initially, the two had a comically adversarial relationship: Vir was guileless, naive and extremely honest and empathetic, making him completely inept at Centauri political process, which irked Londo no end.
The onset of the wars that nearly consume the galaxy in the series – especially his own complicity in their occurrence – changes Londo from an embittered patriot longing for the old days to a more introspective and sympathetic man determined to rebuild not just his own society, but that of others; prior to his coronation as Emperor, he becomes a significant force in emancipating and restoring Narn and in assisting the Interstellar Alliance in bringing peace to the galaxy.
The Centauri state is depicted in decline: it falls prey to decadence and internal politics even while it hungers to return to its days of glory.
In the words of series creator J. Michael Straczynski, he is "overweight, prone to gambling constantly (null-pool is his favorite) and fond of women and drinks".
His cynical political ambition – and his sincere craving to restore the pre-eminence of Centauri Prime – make him into the perfect target for the dark and mysterious Morden, who is secretly representing the Shadows as they work to rebuild their strength.
As Narn fleets continue to be wiped out without any survivors to explain how, Londo takes credit and attracts a great deal of much-desired attention and power, never questioning the consequences of his alliance with the Shadows until it is far too late.
As the events of the Shadow War come to a peak, Mollari is promoted to the position of advisor on planetary security, which requires him to return to his home world.
There, G'Kar will be able to create a security threat by escaping, and in the confusion Londo will kill Cartagia by injecting him with a poison that will cause both of his hearts to shut down.
With his new power, Mollari proceeds to blow up the Shadow base on Centauri Prime, and then execute their agent, Morden – who, he discovers, had Adira killed.
Before his official installation as Emperor Mollari II, Londo confides in his now ex-bodyguard, Ambassador G'Kar, "When we met, I had no power and all the choices I could ever want.
At the end of the fifth season, it is revealed that the Drakh had manipulated the Interstellar Alliance into attacking the Centauri Homeworld and decided they needed Londo to be Emperor.
A few hours before his death, in the events of Babylon 5: In the Beginning, Mollari had a random encounter with two Centauri children (who turned out to be the nephew and niece of Urza Jaddo, while their governess, Senna, proved to be the daughter of Lord Refa).
To commemorate Londo and G'Kar, he orders twin statues of them erected in front of the Centauri Royal Palace, symbolically guarding the city and watching each other's backs.