Knowing that their relationship would’ve been more open under different circumstances is nice.
I do find it weird that she was listed in the credits for both seasons. Her character was more recurring than main. Same with G’Kar’s assistant, who I have been told is now on actor #2.
I think who shows up in the credits has more to do with their contracts rather than how much they're actually in the show. The order they show up and what precedes their credit (staring/featuring/and../etc.) is I think more of an actor's union/payscale thing. I could be wrong as it all gets a little confusing.
Suffice to say, if an actor is in the credits and not showing up is as many episodes as everyone else then they're probably getting paid more per hour worked than anyone, so in this instance I don't think it was about the money so much as her genuinely feeling like she's not being given much to do (which she wasn't because the Narn/Centauri arc was the priority and season 2 had a lot of ground to cover introducing Sheridan.)
Speaking of being the the credits without having much to do; fighter pilot McSmarmy face person who's name I don't quite recall (Keffler?) Was deliberately used the least amount possible because he was the result of the dreaded "studio notes". It's also why he was killed off at the earliest opportunity...which was news to the actor since he wasn't told that was his death scene.
Side note: This was probably mentioned back when O'Hare jumped ship, but while JMS did carefully plot out each character's role, he also knew the realities of TV production meant he'd loose a certain number of cast members of the the course of 5 years, so he was careful to write in what he calls "escape hatches" where a character can be dropped out of the show and their arc role shifted onto someone else.
In the case of Talia this had already happened as she was a replacement character for Pat Tallman's Lyta, who couldn't make it back after the pilot (there was a 12 month gap after all.) Though in a bit of a twist, the plot arc Talia inherited wasn't Lyta's but Takashima's too.
I forget if 'Control' was always to be the means, but one way or another there was always going to be a spy/traitor among the main cast and it was originally supposed to be Takashima. There's still evidence of this in 'The Gathering' as in a blink and you'll miss it shot, you can see she's aiding the Minbari assassin.
Oh and while we're talking about cast member changes and people seeming to disappear there's a reason G'Kar's aide just dropped out of the show; they went through like 4 actresses and eventually just gave up on the character. I may have the sequence of events off a little but IIRC the first actress (who's character name I forget) showed up in exactly one episode before being killed off screen and replaced by N'Toth mid-way through season 1. That actress had the leave at the end of season 1 because her skin reacted *very* badly to the heavy make-up appliances and to such a degree it affected her ability to get other work. Someone else was cast to replace her but for whatever reason she wouldn't' play the role to match the original N'Toth (she's noticeably more bland in season 2) and was just quietly dropped. I forget exactly where the 4th actress fits in; whether she was the second or first N'Toth, but she didn't even make in in front of the camera. Apparently as soon as they got the make-up on her she freaked out and quit on the spot.