1. It's not that G'Kar doesn't like his own species, no matter what the rumours say. (Ah, the rumours, he has heard them all. That he is impotent with the war-like Narn females; that his sexual proclivities are too extreme for any Narn to bear; that it is all an act, and that the Regime has spies everywhere.) The truth is - and who would wish to admit to so mundane a truth? - that it is simply... inopportune. He is busy, now, and there are not that many Narn females on the station in any case. And would they have him molest Na'Toth? He would be lucky to escape with all appendages intact.
Earlier, then, and he simply shrugs and smiles and lets people draw their own conclusions. He lets them think of him as young and lusty and free, and does not mention that this would have been an unlikely life for a young Narn during the Occupation.
(His first time maybe doesn't even count. Certainly it didn't seem to be sexual to his understanding of it, standing naked and awkward and shivering, but the Centauri guard had an entirely different understanding of it.
It is not something he is likely to bring up.)
2. It's not a fetish, not really. Doesn't everyone have the odd thought about sex with an all-knowing partner?
3. He sleeps at the foot of the bed, his knife in easy reach. Mollari protested, waving vaguely at the bed in an exasperated manner and holding forth on self-flagellation and insufferable martyrdom until G'Kar wanted to strangle him with his own nightgown.
"I sleep on a stone tablet, Mollari," he said, amused. "A floor will be indulgent by comparison."
Londo makes a face at this, and mutters something about crazy men and their messiah fetishes, and leaves him be. He strips with quiet efficiency, leaving most of his armour on and only divesting himself of his gauntlets and coat. When he looks up, he finds Londo watching him.
Londo looks anyway. "Nothing," he says. "Good night, G'Kar." He is beneath the sheets already, his nightgown bunched about him as he wriggles down to settle himself on the pillows. His hair fans out across the bedding, black on gold, and there are dark smudges under his eyes.
G'Kar watches him for another moment, before turning away and settling himself on the floor.
(When he closes his eyes, he sees black on gold.)